Low-speed torque or high-speed power — it’s all in the intake!
Words and Photos by Richard Holdener
The single- or dual-plane intake argument is likely as old as the V-8 engine itself. While the 5.0L Ford was originally equipped with factory fuel injection, the basic small-block Ford had been run in carbureted guise for years prior to the introduction of sequential fuel injection. Choosing the proper carbureted intake for your 5.0L Ford is critical for maximum performance, but know that the word maximum might not just mean peak power numbers.
Our test motor started out as nothing more elaborate than a used Ford Explorer motor from a local LKQ Pic-a-Part wrecking yard.
Peak power is one thing, but for many, maximized power deals with power production through the entire rev range. Now, toss in other important factors (at least for street cars) like drivability, fuel mileage, and even torque converter compatibility, and you start to see that man does not live by peak numbers alone. You see, despite similar peak torque numbers, the two Speedmaster intakes tested here offered decidedly different power and torque curves, to say nothing of drivability.
Named after the Australian arachnid, the Funnel Web was designed to maximize high-rpm power production of high-performance, carbureted engines. Like most single-plane designs, the Funnel Web featured a large, common plenum feeding eight individual runners. The high-rise, raised carburetor flange provided a straight shot for airflow entry into the cylinder head. The added height also allowed for an increase in runner length for the four middle (short) ports, always an issue with single-plane intakes on V8s.
Short of a true tunnel ram, it is difficult to have equalized runner length on a single-plane manifold. Unequal runner length creates a situation where some cylinders produce peak power at different engine speeds than others. The Funnel Web design does not allow for true equal runner length between cylinders, but the added height does decrease the difference between the four long and four short runners.
While we all like to brag about the peak power numbers, the reality is the vast majority of carbureted 5.0L engines spend MOST of their time well below that power peak.
The question now is how will the Funnel Web compare to the more traditional dual-plane design? The single- vs dual-plane intake debate comes down a simple matter of operating (engine) speed. The dual-plane manifold, like the Eliminator intake from Speedmaster, was designed to enhance power in the low and mid range, though it pulled surprisingly well on the top end. This combination makes it ideal for the vast majority of street and even street/strip applications. On most performance engines (like our modified 5.0L), the dual-plane will likely sacrifice power at top of the rev range compared to the single-plane design. For a race-only motor, that spends its time at the top of the rev range, racers almost always choose the single plane.
In the end, the owner must decide where power production is most important, as there will ALWAYS be a trade off in power. The question now is how much low-speed torque are you willing to sacrifice for the stellar top-end charge?
Naturally, the debate rages on and on, but perhaps the best way to illustrate the difference in power is to compare them on the dyno. Obviously, the dyno graphs do not directly show things like drivability and mileage, but low-speed torque production provides a strong indicator of both.
To clearly illustrate the power differences between the single-plane Funnel Web and dual-plane Eliminator intake, we assembled a 5.0L test motor. The 5.0L started out life in an Explorer, but was modified for this test with the removal of the factory fuel injection, cylinder heads, and camshaft. In their place, we installed a set of CNC-ported, 11R 170 heads from TFS, an XE274HR camshaft from COMP Cams, and our pair of intakes. Feeding each intake was a Holley 650XP carburetor, while spent gases exited through a set of 1 ¾-inch Hooker headers. Additional performance components employed on the test motor included 1.6-ratio roller rockers from TFS, Fel Pro 1011-2 head gaskets, and ARP head bolts. Prior to testing, we filled the crankcase full of 5W-30 Lucas synthetic oil, then installed the Meziere electric water pump (no other accessories were employed).
With our 5.0L Ford ready to test, we first installed the dual-plane Eliminator intake from Speedmaster. The dual-plane design promised ample torque production and delivered just that. Run with the dual plane, the 302 Ford produced 394 hp at 6,300 rpm and 370 lb-ft of torque at 4,300 rpm. Torque production exceeded 360 lb-ft from 3,700 rpm to 5,000 rpm. After installation of the single-plane Funnel Web intake, the peak horsepower output jumped to 415 hp, but peak torque fell slightly to 365 lb-ft at 5,700 rpm.
Both the peak power and torque values occurred higher in the rev range with the single plane, and (as expected), the single plane traded low speed torque for horsepower gains at the top of the rev range. Above 5,200 rpm, it was all Funnel Web, but below that point, the dual plane offered considerably more torque. The tangled web now (as always) is, where to you most value your power production?
5.0L Ford Intake Test-Eliminator vs Funnel Web (HP) This is a situation you will see time and time again when comparing the single- and dual-plane intakes. The single plane typically makes more peak power, but the dual-plane design counters with more low-speed torque. The crossover point in this test was 5,200 rpm, so you will have to decide where your motor spends more of its time. For an all-out drag race machine that runs from 5,000-7,000 rpm, the choice is obvious, but considerably less so for anything that will see street use.
Ford Intake Test-Eliminator vs Funnel Web (TQ) The torque curve was much more telling, as the loss of low-speed power was more pronounced. For most street, and even dual-purpose, street/strip applications, the extra grunt offered by the dual-plane intake will likely be more useful on a daily basis. If only there was a way to have the grunt of the Eliminator with the high-rpm power of the Funnel Web. The two made similar peak torque numbers (365 lb-ft for the single plane and 370 lb-ft for the dual plane), but the torque curves couldn’t be more different. That is why we test and show the entire power curves, rather than just provide peak numbers.
The right induction system is critical for any 5.0L Ford!
Words and Photos by Richard Holdener
What is the better choice for your 5.0L Ford, carburetion or injection? The question is a simple one, but the answer somewhat less so. Obviously, we would have to be slightly more specific and determine exactly which carbureted and EFI combos we were discussing, to say nothing of what we mean by the generic word “better.” Is all carburetion for the 5.0L Ford better than all injection? Not likely, but nor is the opposite true. I guess the phrase “different strokes for different folks” applies here.
The carbureted 302 contingent that grew up in the late ’60s and early ’70s (actually through the mid ’80s) might feel differently than the 5.0L Ford owners that cut their performance teeth on modern fuel injection. For Ford fans that predate the 5.0L, the complexity of fuel injection doesn’t compare to the simplicity of a good, old-fashioned carburetor.
In spite of the fact the carb guys are carb guys and EFI guys are EFI guys, that didn’t stop us from running a comparison between the two. If nothing else, it should give the two camps even more to argue about. Before we could start testing, we needed to source a few important components, including both induction systems and a suitable test motor.
The test motor was easy enough, as we already had a 5.0L Ford (302 for you carb guys) on hand and ready to run. Much more than a just a stocker, the early 5.0L was recently yanked from an Explorer that wound up in a local LKQ Pic-a-Part. We retained the short block, after stripping off the GT-40 induction system and matching iron heads. Naturally, the stock cam was replaced by a more aggressive variety, in this case a COMP XE274HR grind. The XE274HR delivered a .555/.565 lift split, a 224/232-degree duration split, and 112-degree lsa. This was about as wild a cam as we dared run with the available piston-to-valve clearance.
Once we had the new COMP cam in place, we turned our attention to the cylinder heads. The GT-40 heads on our early Explorer motor were upgraded with a set of 170cc, 11R heads from Trick Flow Specialties. Don’t let the 170cc port volumes throw you; they were perfect for the little 302, and the new 11R heads offered some impressive features. We loved the billet external appearance, but for power, the heads featured full CNC porting (including intake, exhaust, and combustion chambers). Further improving flow were revised valve angles of 11 and 13 degrees (intake and exhaust) and a 2.02/1.60 stainless steel valve package.
Equally important for power were the 56cc combustion chambers, which helped to increase the static compression ratio over the 65cc GT-40 heads. The stock 5.0L (and GT-40 Cobra) featured 61cc chamber heads, but even these did not compare to the small-chamber TFS 11R heads. The heads were shipped with a hydraulic roller spring package that allowed us to safely rev the motor to 6,500 rpm. Covering the 1.6-ratio roller rockers and hardened pushrods was a set of Speedmaster aluminum valve covers.
With our test mule complete, we installed the first of the two induction systems, starting with carburetion. The TFS heads were topped with a polished, dual-plane Eliminator intake. Ideal for any street and even most street/strip applications, the dual-plane design promised (and delivered) a broad torque curve combined with the ability to pull hard up to and beyond 6,000 rpm. The Eliminator intake was combined with a Holley 650 Ultra XP carb, but not before adding an MSD billet distributor and a set of Hooker 1 ¾-inch, long-tube headers.
Run with the dual-plane intake and carburetor, the modified 302 Ford produced 394 hp at 6,300 rpm and 370 lb-ft of torque at 4,300 rpm. Torque production with the dual plane exceeded 350 lb-ft all the way out to 5,400 rpm, and the horsepower curve remained strong past 6,600 rpm. After running the dual plane and carburetor, off it came to make room for the fuel-injected configuration.
To ensure we maximized the power potential of the EFI induction system, we dialed in the air/fuel and timing curves with this FAST XFI management system.
Run with the TFS EFI set up, the fuel-injected 5.0L Ford produced 391 hp and 372 lb-ft of torque. Though the peak numbers were very similar, the injected version offered more power from 4,700 rpm to 6,000 rpm, but fell off to the dual plane out to 6,600 rpm.
Since the 5.0L Ford was already blessed with a set of TFS 11R heads, we decided to make it a family affair by replacing the carburetion with an induction system from TFS, as well. Available in different guises for specific rpm ranges, we chose the Street Heat upper and lower intake. The Street heat featured 12.2-inch runners designed to provide ample torque and power up to 6,000 rpm. If this sounds a lot like the dual-plane intake, you have been paying close attention. Feeding the Street Heat was a 75mm throttle body from Accufab, while fuel was supplied by a set of Accel injectors. Tuning the injected combination was a FAST XFI management system.
302 Ford-Speedmaster Dual Plane vs TFS Street Heat EFI Prior to the test, the 5.0L was upgraded with a COMP cam, TFS 11R heads and 1.6-ratio roller rockers. First run with the Speedmaster Eliminator intake and Holley carb, the modified 5.0L produced 394 hp at 6,300 rpm and 370 lb-ft of torque at 4,300 rpm. Obviously, the combination worked well together, as the 302 just missed reaching the 40-hp mark. The TFS Street Heat EFI upper and lower intake offered nearly identical peak numbers, checking in with 391 hp and 372 lb-ft of torque, but the curves show injection offered more power from 4,700 rpm to 6,000 rpm. The dual plane held the advantage both below 4,000 rpm and above 6,100 rpm.
After dialing in the air/fuel and timing curves, the fuel-injected 5.0L produced 391 hp at 5,900 rpm and 372 lb-ft of torque at 4,200 rpm. Looking at the power curves (see graphs), we see that, despite similar peak numbers, the injected combination offered sizable gains from 4,700 rpm to 6,000 rpm, but the carb combo pulled away on the big end. The dual plane also offered slightly more torque below 4,000 rpm, so let’s get that party started — is the hot setup carburetion or injection?
It is hard to go wrong with bolting on a simple four-barrel carb and dual-plane intake, but might fuel injection be an even better choice?
Words and Photos by Richard Holdener
Though currently the country is caught up in the LS craze, let’s not forget it was the original small block that put Chevy performance on the map. It can be argued that the little mouse motor all but revolutionized the after market industry, and truly earned its legendary status with countless wins in almost every conceivable from of motor sports. If you are new to the small-block Chevy scene, try this simple test. Ask any small-block owner, and chances are they have at least one cool story involving their beloved mouse motor.
Despite the popularity of the LS, the original small block continues to be a mainstay of the performance after market industry. Some guys simply will not switch, no matter how good (or popular) the LS engine family is. Many of these diehards also stick steadfast to carburetion. There is certainly an argument to be made in favor of the wining ways of a carbureted small block, but does that mean it doesn’t respond to fuel injection? That, my friends, is what we were here to find out.
The 305 test mule had been upgraded with a COMP XR276HR-10 cam. The cam offered a .502/.510 lift split, a 224/230-degree duration split, and 110-degree lsa.
There is no denying the simplicity of a simple carburetor. Having run numerous small blocks on both engine and chassis dynos, we concur with the notion that setting up any EFI motor is considerably more complex that its carbureted counterpart. The question now is, does that mean that modern EFI systems have anything to add?
Truth be told, both factory and aftermarket EFI systems (like the FAST XFI system on this motor) have a lot going for them. That Ford, Chevy, and Dodge abandoned the carburetor in favor of electronic fuel injection speaks volumes about its potential. The most obvious benefit offered by injection over carburetion is the ability to properly dial in the air/fuel and timing curves for any combination of load and engine speed.
By contrast, the carburetor is very effective at metering fuel under MOST conditions, but try to trim the fuel by 6 percent at just 3,880 rpm with a carburetor and see what happens. Proponents of carburetion counter with the additional power offered by charge cooling, so we thought we’d take yet another look at carburetion versus fuel injection on a typical small block.
Obviously, the only way to do this was to run the same motor with fuel injection and carburetion. To add a little spice to the recipe, we decided to run different intake configurations as well. Like any comparison, this test was not designed as the final word in the debate, but rather to provide additional fuel for the fire. Both systems provide benefits that may be more or less desirable to the individual, and besides, you will never convert a die-hard carburetor guy over to fuel injection, and vice versa.
The results of this test really were less about carburetion versus electronic fuel injection than the difference in the intake manifold design. The dual-plane, carbureted RPM Air Gap intake offered a decidedly different power curve than the Holley Stealth Ram, irrespective of how the fuel was delivered. Whether injected or carbureted, in the end, it was still a small-block Chevy, and that can only be good.
To illustrate the merits of both carburetion and fuel injection, we decided to apply both to a suitable small block. Rather than choose the more-common 350-inch displacement, we selected a 5.0L, or 305 for those who don’t speak metric. The 305 shared the 3.48-inch stroke of its big brother, but ran a significantly smaller bore of 3.736-inches. The smaller 305 was run in a variety of different cars and trucks, and was even the hot setup for a Camaro back in the late ’80s and early ’90s. Ultimately, the F- body received the 350-inch, L98 TPI motor shared with the Vette.
Using a FAST XFI, we dialed in the air/fuel ratio of the injected small block.
Rather than run the test on a stock 305, we spiced things up a bit by adding a set of TFS Super 23 aluminum heads and a healthy COMP cam. Designed specifically for the small-bore 305 application, the TFS heads dramatically improved the flow over their iron counterparts. Working with extra flow offered by the TFS heads, the COMP XR276HR-10 cam featured a .502/.510 lift split, a 224/230-degree duration split, and 110-degree lsa. We knew the right cam and heads would help better illustrate (and magnify) the differences between the injected and carbureted induction systems.
Run on the dyno in fuel-injected form, the 5.0L produced 370 hp and 349 lb-ft of torque. The injected combo made more peak power, but lost out slightly in torque production to the carbureted combo.
The two-induction system run on the modified 5.0L included our old carbureted-combo standby, the Edelbrock RPM Air Gap intake and Holley 650 Ultra XP carburetor. Always a good combination for a street small block, the dual-plane RPM Air Gap offered an impressive combination of horsepower and torque production. Representing the injected contingent was a Holley Stealth Ram intake. The Stealth Ram was essentially a tunnel ram converted for EFI use with injector bungs. The tunnel-ram lower intake was combined with a box upper manifold designed to accept a dual 58mm throttle body.
305 Chevy-RPM Air Gap vs Holley Stealth Ram Note how the dual-plane intake improved torque production lower in the rev range, while the Stealth Ram offered gains on the top end. The peak numbers differed by just 7 hp and 4 lb-ft, but the carb combo offered as much as 20 additional lb-ft down low. Past 5,000 rpm, the Stealth Ram pulled ahead by 10-11 hp. Though the WOT test showed the differences in power, what it doesn’t show you are things like fuel mileage and drivability, which would likely be better with the fuel injection.
In the end, the two forms of induction system produced similar peak power numbers, with the Air Gap and Holley checking in with 363 hp at 6,100 rpm and 353 lb-ft of torque at 4,500 rpm. The Stealth Ram raised the horsepower peak to 370 hp at 6,000 rpm, but peak torque dropped slightly to 349 lb-ft at 4,800 rpm. Despite the slight differences in peak numbers, the curves were dramatically different, with the carb combo offering better low-speed power up to 4,700 rpm, but the Stealth Ram took over past 5,000 rpm. No matter how you slice it, high-tech or high-torque, carbs or computers, as long as it goes on a small-block Chevy, it’s a win in our book.
Choosing the right cam can make or break your small block build.
Words and Photos by Richard Holdener
Let’s face it, small-block Chevys are awesome in every way, no matter what displacement you choose. Sure, a 283 is better than a 265, as is a 350 better than the 327, but, no matter which displacement you choose, they all have one thing in common. Scratch that, the one thing all owners of the different displacements have in common, is a desire to make more power.
The 265 and 327 owners look longingly at the extra torque offered by the 283 and 350, and they in turn, all look up to the mighty 400 small block, but we have gone off on enough of a tangent here. The topic for today is the quest for more power, regardless of the cubic inches. It is with this in mind that we set off to compare a couple of cam profiles offered by COMP Cams on a mildly modified small block. Normally we’d choose a run-of-the-mill 350 Chevy; after all, it was the workhorse of the small block lineup. Rather than follow the crowd, we decide to take the road less traveled and perform our mods on a 305 Chevy (a.k.a the 5.0L).
More than just a smaller motor compared to the 5.7L 350, the 5.0L 305 was a different animal. Where the 327 and 350 shared the same 4.0-inch bore size and differed in stroke length, the 305 shared the 3.48-inch stroke of the 350, while the difference in displacement was made up in the bore size. Rather than the desirable 4.0-inch stroke offered by the 327 and 350, the 305 featured a 3.736-inch bore. More than a simple drop in displacement, which obviously decreases power, the smaller bore size also limits head flow and available (performance) cylinder heads. Where the larger-bore small blocks can enjoy the plethora of available Chevy heads, the 305 is limited to just a couple.
We then added the first, and wilder of our two COMP cams. The XR276HR-10 cam offered a .502/.510 lift split, a 224/230-degree duration split, and 110-degree lsa.
To take advantage of the available cam timing, we also upgraded the cylinder heads. The stock iron 305 heads were replaced by a set of aluminum Super 23 heads from TFS.
Luckily, that list of available heads included the desirable TFS Super 23 heads. The simple fact the heads were aluminum was a significant step up the performance ladder compared to the iron heads used on our TPI 305. The Super 23 heads offered a dramatic increase in flow over the stock iron heads (from any 305), thanks to 175cc intake ports, a 1.94/1.50 valve package, and 56cc combustion chambers.
Since the camshaft is the heart of any performance motor, we decided to compare a pair of different cams on the TFS-headed 305. In the more streetable category was a 268XFI cam that offered a .570/.565 lift split, a 218/224-degree duration split, and a 113-degree lsa. In the slightly wilder corner was a COMP XR276HR-10 cam, that came to battle with slightly less lift (.502/.510), slightly more duration (224/230-degree split), and a tighter, 110-degree lsa.
We were most curious to see if the extra lift offered by the XFI cam could compensate for the added duration offered by the XR grind, all without sacrificing idle quality and drivability. To add a little extra spice to the test, we also tested both cams in carbureted and injected trim. After all, the XFI cam was designed with fuel injection in mind, so we wanted to make sure it had a proper home. As we would find out, the difference in the cams was consistent whether equipped with carburetion or fuel injection.
For the first cam test, we equipped the modified 305 with an Edelbrock Performer RPM Air Gap intake and Holley 650 Ultra XP carburetor. Ever the popular combination for any small block, the dual-plane RPM Air Gap never fails to offer a balanced combination of horsepower and torque. Equipped with the smaller XFI cam, the carbureted 305 produced 361 hp at 6,000 rpm and 350 lb-ft of torque at 4,400 rpm.
We then swapped in the 268XFI-HR13 cam from COMP Cams. The XFI grind offered less duration than the XR276 cam, but slightly more lift and a wider lsa.
After installation of the hotter XR276 cam, the peak numbers changed slightly to 361 hp at 6,000 rpm and 353 lb-ft of torque at 4,500 rpm. A peak at the respective power curves (see graph 1) reveals that the 276 cam offered slightly less power down low, but slightly more in the middle and upper rpm ranges. The differences were only slight, not really enough to warrant choosing one over the other, unless you were more interested in things like idle quality and drivability.
Satisfied we had coaxed every last ounce of power out of the carbureted combos, we swapped out the carbureted induction for fuel injection. The EFI set up included FAST XFI controlling the injectors on a Holley Stealth Ram intake. The question now is would the injected small block respond differently to the pair of cam combos than its carbureted counterpart?
The Stealth Ram lower was topped with this upper intake and dual 58mm throttle body. Run with fuel injection, the cam swap netted the same results as carburetion, with the smaller XFI cam offering more power at the very bottom of the rev range, but less at the very top. For most of the curve, there was little to choose from between the two cams.
Once again, we ran the pair of cams, and the injected small block responded with similar differences in power. Equipped with the XFI cam, the injected 305 produced 367 hp at 6,000 rpm and 349 lb-ft of torque at 4,800 rpm. After installation of the other X cam (with more duration and a tighter lsa), the injected small block belted out 370 hp at 6,000 rpm and 349 lb-ft of torque at 4,800 rpm.
Carbureted 305 Chevy Cam Test-XR276HR vs 268XFI HR13 Run with the Performer RPM Air Gap and Holley 650 Ultra XP carb, there was little difference between the two COMP cams. The XFI offered more power down low, from 3,000-3,900 rpm. The XR cam offered 2-3 extra hp up to 5,000 rpm, then bettered the smaller cam once again past 6,000 rpm. In truth, you would be hard pressed to tell the difference in power behind the wheel between the two cams, but the XFI did offer improved idle quality, and likely, drivability compared to the increased duration (and tighter lsa) of the XR grind.
Fuel Injected 305 Chevy Cam Test-XR276HR vs 268XFI HR13 Thinking we should combine the XFI cam with fuel injection, we ran the same cam test after equipping the 305 small block with a Holley Stealth Ram. Though the intake was decidedly different that the dual-plane, carbureted manifold, the results were very similar. The milder XFI cam once again offered improved torque up to 3,900 rpm, then fell behind the XR276 cam above 5,800 rpm. There was a slight bump in power (1-2 lb-ft) from 4,400-4,700 rpm, but that was just splitting hairs.
As with the carburetor, the smaller XFI cam offered more power up to 4,000 rpm, then the two produced near identical curves up to 5,700 rpm. From there, the extra duration of the XR cam offered minor gains. Given the minor differences, in the battle of these Xs, the winner will be any small block with either cam.
Was our twin-turbo big block ready for the ice-bucket challenge?
Words and Photos by Richard Holdener
What’s not to love about boost, especially when it comes from a pair of properly sized turbos feeding a stroker big block? Such was the case recently with our 540-inch crate motor from Blue Print Engines. Now, don’t get us wrong, we love boost, especially from turbos, but beware, there is (as always) a negative side to the otherwise amazing positive pressure. One of our least favorite laws of physics dictates heat is an unfortunate byproduct of compression. I just knew there was a catch! That boost that we all know and love comes with a price, and that price is unwanted heat build up.
As we all know, heat is not only the enemy of power, but can also cause serious engine damage in the form of detonation. Curse you, physics for creating this love-hate relationship. Restricted by physics, the question now becomes, how does a boost builder stand the heat without getting out of the kitchen?
The answer to the ongoing battle with the boosted byproduct is obviously intercooling. As previously indicated, the boost pressure supplied by our turbos (or any form of forced induction) increases the temperature of the inlet air. Remember, hot air is bad! Luckily, physics also provides the answer to the hot-air blues, and it’s a simple matter of running said air through a heat exchanger.
Though we employed an air-to-water intercooler in this test, know that air-to-air systems work well, they just don’t allow you to run ice water as the cooling medium. They do, however, allow other coolants —water misting, CO2, and even nitrous oxide — to be sprayed on the core to further enhance the cooling properties of the air-to-air core. For this test, we relied on an air-to-water intercooler from CX Racing. Designed for high-horsepower, twin turbo (or blower) applications, the core featured a pair of 3-inch inlets and a single 3.5-inch outlet. Having easily exceeded 1,300 hp with this core, it was perfect for our ice-bucket challenge.
The idea behind the challenge was to illustrate the benefits of further cooling the charge air. The air-to-water intercooler was already on hand to drop the inlet air temps out of the turbos, but we relied on ambient (84 degrees) dyno water to run through the core. Not terrible in the grand scheme of things, especially running just a tad over 10 psi, but we knew there was even more power to be had with further chilling.
To illustrate these gains, we enlisted the aide of a stroker big block supplied by Blue Print Engines. The 540-inch big block featured plenty of strength, thanks to a 4-bolt block (BPE’s own casting) combined with a forged trio that included the crank, rods, and pistons. Designed for power-adder use, the crate motor also featured a static compression ratio of 8.5:1, a set of rec-port, aluminum heads, and a solid-roller cam profile. Supplied as a long block, the BPE crate motor was perfect for our intercooler test.
Naturally, the intercooler test required something more than a crate motor and an intercooler core, so we enlisted the aide of the turbo experts at Lil John’s Motorsports. They supplied a pair of Borg Warner 475S turbos, each capable of supporting up to 1,000 hp, so the pair was more than adequate for our needs. The turbos were fed by a set of tubular turbo manifolds whipped up by Jason over at J-Fab. Using V-band flanges, the turbo manifolds fed J-bends that featured both dedicated T4-turbo mounts and provisions for our Hyper-Gate45 waste gates supplied by Turbo Smart.
Using aluminum tubing from CX Racing, we connected the turbos to the intercooler core and routed the discharge to the Wilson throttle body and inlet elbow and. The motor was also configured with 120-pound Holley injectors, an Edelbrock 454-R intake, and shortened valve cover swap from Speedmaster to help clear the 4-inch exhaust from the turbo. In addition to the 45mm Hyper-Gates, Turbo Smart also supplied the necessary Race-Port blow-off valve. This was necessary to eliminate the pressure surge that occurs during high-boost/rpm, lift-throttle conditions.
The first order of business was to run the turbo motor with the dyno water flowing through the intercooler core. Running waste gate springs designed to provide 10 psi, the peak boost pressure registered during the run reached 10.5 psi. Run at this boost level with fixed timing and an air/fuel ratio of 11.8:1, the twin-turbo big block produced 1,081 hp at 6,100 rpm and 1,018 lb-ft of torque at 5,000 rpm.
Run with ice water flowing through its veins, the twin turbo motor pumped out 1,109 hp and 1,066 lb-ft of torque. When it comes to turbo motor, ice is nice, nice, baby!
Next up, we plumbed our ice water system using a fuel cell and a pair of intercooler pumps. The 10-gallon cell was first filled with ice to the brim, then with water. After verification the system was pumping ice-cold water through the core, we once again ran the turbo motor in anger. Run with the ice water, the inlet air temps dropped by more than 25 degrees, and the power output jumped to 1,109 hp and 1,066 lb-ft of torque.
Twin Turbo BPE 540-Dyno vs Ice Water (10.4 psi) As is evident by the graphs, replacing the 88-degree dyno water with 34-degree ice water made a significant change in the power output of the twin turbo 540 big block. Equipped with a pair of Borg Warner 475S turbos from Lil John’s Motorpsorts, the BPE 540 crate motor easily exceeded 1,000 hp by producing 1,081 hp at just 10.4 psi. Things stepped up in a big way once we added the ice water system to the intercooler core, as the power output of the 540 jumped to 1,109 hp. In some areas, the ice water netted improvements of more than 50 lb-ft of torque, but the gains diminished slightly at the top of the rev range. We suspect the flow rate of our two intercooler pumps was inadequate, but either way, we know the ice water is a serious weapon when looking for extra power.
Twin Turbo BPE 540-Dyno vs Ice Water (Boost) Naturally, we data-logged things like boost and charge temperature when testing. This graph shows the boost actually dropped slightly after introduction of the ice water, despite no changes to the waste gate spring (we ran no controller). The difference was as much as 3-4/10ths of a pound in favor of the dyno water, so if we compared at the same boost level, the gains might be even more significant. No wonder why drag racers always run ice water in their turbo motors, as the gains would be even more significant at higher boost levels.
We suspect our intercooler pumps were not up to the task of maintaining proper flow, as the power gains diminished at higher engine speeds, but we still showed the importance of ice water on a turbo application. Know also that the gains would be significantly higher at elevated boost levels, where the inlet air temps out of the turbo might exceed 300 degrees.
The Edelbrock Pro-Flo 3 offers refinement among an industry full of quick-fix EFI systems. There are reasons a multi-point fuel injection system that uses sequential fuel timing to add a level of throttle response that is impressive.
Words and Photos by Jeff Smith
All the fuss over quick-swap throttle body EFI conversions tends to overshadow one of its primary benefits. The original and still the best idea is to place an injector directly over each intake port and then sequentially time the fuel to arrive just before the intake valve starts to open. This eliminates the issues of wet-flow intake manifold attempts at compensating for fuel that has a bad habit of going where it wants — instead of where it’s supposed to go. This leads to rich and lean cylinders and less than ideal performance.
Edelbrock knows all this, of course. They’ve been in the intake manifold business longer than anybody else. Their most recent development is dubbed the Pro Flo 3, a complete multi-point EFI system that employs preassembled injectors, fuel rails, sensors, and throttle body, all mounted on an Edelbrock EFI single-plane intake manifold. Add in a highly accurate optical sensor distributor and complete sequential control over the fuel and ignition system and that adds up to a great system. Then, Edelbrock spiced it up with a wireless Android tablet that puts you in full command of a very sophisticated EFI package.
The Pro-Flo 3 system includes a single-plane EFI manifold with the injectors, fuel rails, and even the coolant sensor already in place. The system is accessed by a handy wireless Android tablet. You will need a high-pressure, return-style fuel delivery system and a regulator.
Just like many of the other self-learning systems, the Pro-Flo 3 takes basic engine inputs to create a
Previously, we had installed an Aeromotive Phantom in-tank fuel pump system that includes a return. We installed this a couple of years before the Edelbrock system, and it has performed flawlessly.
beginning fuel map and then uses the included wide-band oxygen (WBO2) sensor as feedback to learn the minor tuning details to adhere to your specific engine’s needs. You tell the system your desired idle, cruise, and wide open throttle (WOT) air/fuel ratios, and the system learns and applies all the in-between details.
Something this highly developed demanded more than just a cursory overview. The best way to do that was actually install the system and then do a firsthand evaluation. We talked with Edelbrock’s Eric Blakely and scheduled a time to take our ’65 El Camino down and install it right on premises. That doesn’t mean we couldn’t have done the job in our shop, as the swap went very smoothly. Our real reason was more pragmatic — they had more room in their shop!
We had a slight advantage over perhaps a first-time installer because we had previously installed a couple of competitive self-learning systems, which required a proper high-pressure fuel delivery system. This is a critical step toward any successful fuel injection system. The best choice is an in-tank pump with some version of either a fuel reservoir or fuel pickup system in the tank that is not subject to uncovering the pickup due to sloshing fuel. Our choice was the Aeromotive Phantom system using Aeromotive’s Stealth 340 pump that offers more than sufficient fuel volume and pressure to feed our mild little small block.
With that accomplished, the next step was to remove the existing Edelbrock carburetor and Performer RPM dual-plane intake and MSD distributor. We would not be re-using any of these parts. Spearheading our installation was Edelbrock’s David Shaw. The Pro-Flo 3 system comes with the fuel injectors, fuel rails, throttle body, and the coolant sensor already assembled, so all we had to do was perform the intake swap.
We also wanted to use the Pro Flo 3 ECU to control our two Spal electric fans, which required adding two small white wires to the harness. Fan 1 connects to the position shown with the arrow (pin 16), while the second is the very last pin position. Reading the instructions, we learned there’s a plastic lock that must be released to push the pins in place and then relocked.
We also dropped in the optical distributor that’s part of the system. The distributor has Number 1 cylinder stamped into the body, which helps to align the rotor. The distributor cap only installs one way, so make sure you get it right.
Shaw cleaned the old gaskets and replaced them with Edelbrock gaskets from the kit. Our engine was equipped with Vortec heads, which use a specific intake bolt pattern, but that was the only change from a typical small-block Chevy. Shaw had previously set the engine at 10 degrees before top dead center (BTDC), so once the intake was back in place, he dropped in the distributor and lined up the rotor pointing to the stamped “1” in the distributor body. This ensures the timing will be close. We also plugged an open coolant hole in the front of the manifold with a pipe plug.
The most time-consuming effort to installing the Pro-Flo 3 system was simply executing where to mount the ECU and how to route the wiring. We decided on a position in the front left corner, using an aluminum mount for a fan controller that we no longer needed because the Pro-Flo 3 would control our twin electric fans. We mounted the ECU and then routed the wires underneath the fender to camouflage as much as possible.
Before we routed the harness, we had to relocate the ignition coil, since there was no provision for a coil on the intake manifold as before. We found a simple coil mount bracket that allowed us to mount it to the back side of the driver side cylinder head. Originally, we routed the two orange and black wires from the MSD to the coil alongside the ECU wiring. But later, we decided this might cause interference with the ECU and re-routed them to the coil around the passenger side, to maximize their distance from the ECU. We did not have any problems, but we thought this was still a good idea. The MSD (or any CD system) shoots 500 volts through these wires to the coil and can cause interference problems if bundled with the main wiring harness.
The Pro-Flo 3 does not require a CD ignition box, however. A separate ignition harness that will connect directly to the coil is also included. This system uses the optimal trigger in the distributor to send a signal to the ECU, which then drives the coil with an internal module similar in process to what is used in an HEI distributor. This makes for a very compact, yet simple inductive ignition system.
With the distributor and coil mounted, we moved to the fuel delivery side of things. Edelbrock sets the manifold up for a single feed into the fuel rail on the passenger side. This interfered with our fitting for the heater hose. We could have relocated the fuel inlet to the rear of the manifold, but the cross-over hose didn’t fit as well in the front, so we elected to move the inlet to the driver side. There is a schematic in the instructions that indicates you must use a return-style regulator, but one was not included in the Pro-Flo 3 kit. Most EFI-style return regulators have a fuel inlet on one side with regulated pressure on the opposite and the return on the bottom. This is how we configured our regulator.
We had also previously installed a WBO2 in the exhaust, so that made adding this sensor a matter of merely bolting it in place. As a suggestion, performing all the ancillary jobs like adding the fuel pump and the return fuel system, along with the WBO2 sensor, are all projects that can be done before actually installing the EFI system. This will make the final part of the project move much more quickly.
With all the connections completed, we double-checked our hose connections, refilled the coolant, and we were ready to fire the engine. This is when we followed the Edelbrock instructions to configure the software package for your particular engine. Using Setup Wizard in the supplied wireless tablet, we plugged in all the details for our engine, including displacement (350c.i.), camshaft profile (mild 210-230 degrees), 58 psi for fuel pressure, 29 lb-hr injectors, and the manifold Pro-Flo 4150.
We had already hooked up a timing light and were ready to start the engine, but we discovered it wouldn’t fire. A quick check with the timing light determined we had no spark. That quickly led to discovering we had relocated the switched power connection for the MSD, but it was not hot during cranking. We quickly rectified that situation back to its original harness connection, and the engine immediately started up and idled.
The next step was to set the base timing at 12 degrees BTDC. This is done by using the tablet to lock the timing so the distributor can be adjusted to indicate a base timing of 12 degrees BTDC on the harmonic balancer. This confirms that all timing commands from the ECU will be what the engine actually experiences.
With that accomplished, we then set the idle speed target at 750 rpm and adjusted the idle speed screw on the throttle body until the idle air control (IAC) percentage was at 10 percent. This was extremely simple compared to far more complex adjustment procedures we have experienced on some of the less expensive throttle body systems. After the TPS was calibrated, this completed the setup, and we were ready for our test drive.
Once the engine was up to operating temperature, we noticed a slight hesitation just off idle when we let the clutch out on our four-speed, 3.08:1 geared combination. We added a couple of points of acceleration enrichment, which helped, but didn’t quite eliminate the problem. We spoke later with Edelbrock engineer Mark Honsowetz who said our engine application is their most popular, with excellent feedback from early customers. He said it’s possible that sometime during the learning process, the system may have suffered a learning hiccup. His suggestion was to reload the system and try it again. We did, and this basically eliminated the off-idle lean stumble. This made sense because early on, the system ran really great.
But even before we made those changes, it was immediately apparent with our first test drive that the engine just felt better and seemed to respond very quickly to throttle. But more than anything, the engine just felt smoother. A friend went for a ride with us the next day, and he also commented on how smooth it was running.
The tablet displays a nice, bright image that is very easy to read even in bright sunlight. In just a few minutes of running time, the correction factor at idle is very low at 2 percent, as you can see from the set point AFR at 13.4:1 to the actual 13.3:1. There are several different displays from which you can choose.
While there are probably lots of theories, we attribute this to the fact the injectors are now located directly over each intake port, along with the inherent advantages of sequential or timed injection. Early multi-point injection systems from the ’80s used what is called batch injection, where the injectors fire in batches. Sequential fuel injection is also called timed injection, where the injector fires just as the intake valve opens. There are no real power benefits to sequential over batch, but there are some small gains to be had with throttle response and drivability, which is what we noticed through the seat of our pants and plenty of time behind the wheel.
Another side benefit we really haven’t mentioned much is the wireless Android tablet that’s part of the system. Not only is it handy to have a large, full-color screen to look at and use as a digital gauge package, but it’s also pleasant not to be tethered to the car. The system has sufficient signal strength to allow you to walk a few feet away from the car and still monitor or input changes to the system. Blakely also mentioned that if you already own an Android tablet, you can purchase a Pro-Flo 3 without the tablet and easily upload the software.
We also covered the exposed EFI wiring with some Russel’s Wrap-It over sleeve and the final addition of a new Edelbrock chrome air cleaner. We also installed the inlet air temperature sensor inside the air cleaner housing, and with that, we were all finished and ready to hit the road.
If your car is not set up for EFI with a fuel delivery system, adding that could add a day or so to the time required for installation. We spent a couple of days performing our installation that, for once, was not in thrash mode. We took our time installing this system, so it took longer than it should have because we did not rush and make a mistake. Except for the hiccup with the switched power, it all went very smoothly.
We’ve already put about 500 miles on the system, and compared to all the previous self-learning EFI systems we’ve played with, the Pro-Flo 3 has to rate right up near the top for ease of installation (if you don’t count installing the manifold), minimal tuning, and overall drivability and performance. We’ve already decided this is a keeper system. It will be a hard sell for anyone to convince us to remove this Pro Flo 3 in lieu of something better. Why mess with success?
Idle Vacuum Settings
The cam timing input in the early configuration asks for the duration numbers. If you are not sure of the numbers, this chart lists idle vacuum ranges for each of the three different cam timing areas. The Mild Cam is by far the most popular.
Horsepower comes from engines with the right mix of cylinder pressure combined with the right octane fuel. If too low an octane fuel is used, the engine can detonate. Conversely, too much octane, and power remains high, but the cost is higher with no performance gain. The trick is knowing the right mix.
Words By Jeff Smith/Photos By Jeff Smith and Rockett Brand Racing Fuel
This is the Golden Age of horsepower. Never has it been so easy to make big power numbers. Even truck engines now make more than 400 hp. That power comes from cylinder pressure pushing down harder on those pistons to spin the crank. As cylinder pressures rise, octane requirements also increase, but often for reasons you might not realize. We talked with Rockett Brand Racing Fuel VP of Engineering Tim Wusz and President Jack Day, who each gave us some insight into techniques you can use to feed the proper fuel to fire your engine.
Some enthusiasts mistakenly think octane has a mystical power-adding effect so that merely using a higher octane fuel will bump the power level. This is not true; octane is just one of numerous gasoline components that affects power. Essentially, octane is present to prevent the onset of detonation, commonly described as the “knock” that results from uncontrolled combustion occurring after the spark plug has fired.
All gasoline is rated with an Anti-Knock Index, or AKI. This is a rating of the average of the fuel’s Research Octane Number (RON) and the Motor Octane Number (MON), or RON + MON / 2. Of the two numbers, the MON is the more important for performance engines. Rockett’s 100E fuel has a RON of 105 and a MON of 97, which gives it an AKI of 101 — rounded down to an even 100.
While we think of combustion as a single explosion, the truth of the matter is that after the spark plug ignites the mixture, the effect in the combustion space is more like a grass fire burning across a prairie, with the piston top being the prairie surface enclosed by the combustion chamber. As the fuel and air burn across the top of the piston, pressure and temperature increase. If the fuel has insufficient octane, the fuel and air toward the far side of the combustion chamber can spontaneously explode due to the high heat and pressure. This creates a pressure spike that makes that distinctive detonation rattle. To combat detonation, we need a higher octane fuel.
For street engines, premium pump gasoline ranges between 91and 93 octane. Performance street engines, especially those equipped with power adders like nitrous oxide, superchargers, or turbochargers, can radically increase the cylinder pressure, which demands a higher octane. Rockett Brand offers a 100 octane fuel that is lead-free and also completely street legal, even for later model engines with catalytic converters. This is a high-quality, high-octane fuel perfect for power-adder applications or those engines with high compression ratios.
This is the blending chart for mixing 91 octane pump gasoline with 100 octane Rockett race fuel. The 100 fuel is unleaded and legal and safe to use even with new, catalytic converter-equipped cars.
For example, it’s entirely possible a mid-effort centrifugally-supercharged small-block street engine making 600 hp from 8 pounds of boost might only require 96 octane fuel to make this power. While running 100 octane fuel will certainly offer a level of added insurance, this also comes at a cost, since 100 octane race gas tends to be a bit more expensive than 91 octane premium fuel.
To benefit street engine users, Rockett has created a blending chart (www.rockettbrand.com) that reveals how mixing 100 octane Rockett fuel with 91-94 octane pump premium can create the octane rating that will fit your specific purposes. We’ve discovered our little 4.8L LS truck engine at 6 psi of boost only requires 96 octane fuel to make 500 rwhp. Our testing reveals that raising the octane beyond 96 does not improve power. So, we used Rockett’s blending chart for 91 pump fuel to create a 96 octane fuel. By mixing 6 gallons of Rockett 100 octane race gas with 5 gallons of 91 octane pump gas, we come up with 11 gallons of fuel with an octane rating of 95.9 octane — pretty close to what we need.
This is the blending chart for mixing 93 octane pump premium with 100 octane Rockett race gas. Note that starting with a better pump fuel means less high octane gas to create the same effective blend octane rating.
By starting with a higher 93 octane pump fuel, you can see on Rockett’s chart that you need less race gas to make the same number. Mixing 7 gallons of 93 with 5 gallons of 100 race gas will also produce the same 95.9 octane fuel, but you end up with 12 gallons of good fuel, instead of 11.
Besides the fuel’s octane rating, there are several other factors that affect an engine’s octane requirement. Ignition timing is clearly the most critical factor. Often, the difference of a degree or two can reduce an engine’s octane requirement without causing a drastic loss of power. In a supercharged application, it’s not uncommon to find that reducing the ignition timing four degrees from 30 to 26 will reduce the torque 30 lb-ft. While significant, this also allows the use of lower octane fuel for cruising. For ultimate drag strip performance, it’s easy enough to increase the octane back up to 98 or 100 to prevent detonation problems.
This is our supercharged 4.8L truck engine equipped with a blow-through carbureted Vortech V-3 supercharger. This iron-block truck engine sports a static compression ratio of 10.0:1 with lightly ported heads and a mild cam and makes 600 hp at the crankshaft, with only 6 psi of boost. We made this power using a 50-50 mix of Rockett 100 gas and 91 octane pump gas, which from the blending chart is a 95.5 octane rating.
Other issues that also affect an engine’s octane sensitivity are factors such as atmospheric pressure, inlet air temperature, and humidity. A combination of high temperature, high pressure, and low humidity are akin to a perfect storm where all three factors contribute to demand a higher octane number. Among the most impressive numbers Wusz offered is how even a slight inlet air temperature increase can affect octane requirements.
Wusz told us that back in the ’70s, the car companies performed extensive inlet air temperature research and discovered every 25-degree increase in inlet air temperature pushed an engine’s octane demand by one full number. As an example, if we pull into the engine under-hood inlet air that is 50 degrees above ambient (an increase from 70 to 120 degrees), this will put the engine’s octane requirement two full numbers higher, or the equivalent demand of 91 to 93 octane fuel.
This is one explanation why your engine seems to run better on cool days. Cool air is not only denser with more oxygen per cubic feet of air, but it’s also less prone to detonate. Have you ever wondered why engines tend to easily detonate when they become overheated? With the engine at the extreme high end of its operating temperature range, the heads and intake are also much hotter. This heats the air as it enters the cylinders. Hotter air is more prone to detonation, as evidenced by the 25 degree rule. It all makes sense when you think about it.
With a full load of Rockett 100 fuel, our little 4.8L motor with the same Vortech supercharger spiked the boost up to 11.5 psi and made 630 hp at 6,800 rpm and was still climbing when we shut the test down. We only stopped because this engine still has the stock connecting rods that are a bit questionable above 7,000 rpm. With good rods and pistons, we would not hesitate to take this right past the seven-grand mark. It might make 650 hp!
Day also emphasized the discussion of octane numbers is of full numbers and not octane points. Off-the-shelf octane boosters often make claims that mixing their special sauce will improve octane by as many as three or four points. Most enthusiasts assume those “points” to be whole numbers, when in fact an octane point is one-tenth (0.10) of a whole number. So, an improvement of three “points” from a 91 octane fuel base would only increase the fuel’s AKI to 91.3. As you can imagine, this is negligible compared to moving the AKI from 91 to 96.
Armed with this new-found information, there are several approaches you can make toward improving engine performance without purchasing octane that your engine might not necessarily demand. Knowledge, in this case, really is power.
Source: Rockett Brand Racing Fuel; rockettbrand.com
If you are looking for some extra power from your carbureted Ford, why not try carb spacers!
Words and Photos By Richard Holdener
Having recently run a single- vs dual-plane intake test, we always come away wanting the torque of the dual plane with the top-end charge of the single plane. Obviously, having our cake and eating it too is a difficult, if not impossible, proposition. This got us wondering if there is a better compromise to be had with carb spacers, instead of replacing the entire intake?
Given the open plenum, the single-plane intake is often less receptive to carb spacers than the dual plane. The reason for this is the dual-plane design is actually altered with the installation of a spacer, especially an open spacer that all but eliminates the divider inherent in the dual-plane design. Eliminate or reduce the wall on the divider and you can significantly alter or fine tune the shape of the power curve. Drag racers have been doing this for years, often with excellent results. The question now is, how much power can we unearth from a typical street/strip small-block Ford with a little fine tuning?
Hardly a high-dollar crate motor, our 5.0L test mule came straight from a local LKQ Pic-a-Part. To prepare for the dyno session, the motor was stripped to the short block to facilitate a few performance modifications.
To test the effectiveness of carb spacers, we needed several things, including a test motor, a suitable dual-plane intake, and the necessary carb spacers. Taking these things in order, we ventured over to our local LKQ Pic-a-Part and snatched up a 5.0L Ford. Whether it came from a truck, Explorer, or passenger car (like a Mustang or T Bird) mattered little to us, as we planned on replacing the entire top end, including the camshaft. What we did want was a late-model, hydraulic roller motor, which ultimately came from a Ford Explorer (thnx Mark Sanchez).
The 5.0L was quickly stripped of its GT-40 heads and intake, along with the wimpy factory cam. Our early Explorer 5.0L did not yet possess the later GT-40P heads, so save the emails. In went our favorite 5.0L bump stick from COMP Cams, the XE274HR grind that offered .555/.565 lift split, a 224/232-degree duration split, and 112-degree lsa. The cam was run with the factory lifters, despite the significant amount of mileage.
With our new cam in place, it was time to improve the head flow. Replacing the stock iron heads was a set of 170cc 11R heads from Trick Flow Specialties. In addition to looking like externally like billet heads, the little 11Rs offered an impressive list of features. The heads featured full CNC porting of the intake, exhaustm and combustion chambers, revised valve angles (11 & 13 degrees), and a 2.02/1.60 stainless-steel valve package. The 11R heads were also available with 56cc combustion chambers to increase the static compression ratio over the typical 61cc chambers offered on stock or many after market 5.0L heads.
Available with different spring packages, we selected appropriate springs for our XE274HR hydraulic roller cam. The spring package employed on the 11R heads allowed our 5.0L to rev cleanly past 6,500 rpm. In addition to the heads, TFS also stepped up with a set of 1.6-ratio aluminum roller rockers and hardened pushrods. All this hardware was tucked under a set of Speedmaster aluminum valve covers.
To feed the 11R heads, naturally, we needed the proper dual-plane, which Speedmaster supplied in the form of a polished Eliminator intake. The dual-plane design promised ample torque production with plenty of peak power and delivered just that. The test mule was completed with an MSD ignition, Holley 650 Ultra XP carb, and Hooker 1 ¾-inch, long-tube headers.
Off came the Wilson open spacer to make room for the 4-hole design.
Run with the 4-hole spacer, the power output improved by 5-6 hp and never lost any torque compared to the intake alone.
Run with the dual-plane Eliminator, the modified 5.0L Ford produced 394 hp at 6,300 rpm and 370 lb-ft of torque at 4,300 rpm. Torque production exceeded 360 lb-ft from 3,700 rpm to 5,000 rpm. The first carb spacer from Wilson Manifolds to be run was a 1-inch, open design. Equipped with the open spacer, the peak horsepower number jumped to 402 hp at 6,400rpm, while the peak torque remained at 370 lb-ft, but at a higher 4,800 rpm.
After replacing the open spacer with the 1-inch, 4-hole design, the peak torque once again remained at 370 lb-ft, but it occurred back at 4,300 rpm. The peak power output checked in at 399 hp, meaning the 4-hole fine-tuned a little extra low-speed torque than the open, but was missing the extra top-end power. Such is often the case when tuning; a little more here often means a little less somewhere else, and we are fine with that.
The camshaft is the heart and soul of any performance engine, and no one knew this better than the bootleggers of the Prohibition era. For those 20-somethings out there who might not know what bootleggers are and why they were so bad ass, a quick trip to Wiki is in order, but here’s the condensed version. Back in 1920, the 18th Amendment officially ushered in the prohibition era. Contrary to popular belief, the consumption of alcohol was never made illegal. Instead, prohibition dealt with the supply side, including the manufacturing, sale and (most important for our story) transportation of alcohol.
The demand was high in the roaring 20’s and early 30’s right up until the 21st amendment abolished prohibition in 1933. During this 13-year period, the hills rang out with the sound of bootleggers roaring through the back roads with trunk loads of moonshine to help supply the hoards of thirsty Americans. To keep their junk in the trunk out of the hands of the boys in blue, naturally, bootleggers embraced performance camshafts. Just like their bottles of shine, all the performance they needed came wrapped and delivered in a neat wooden box. For bootleggers, the right cam might just be the difference between a trunk load of happy customers and a night in the slammer.
Lunati’s Bootlegger Camshafts have successfully captured the outlaw spirit and performance of these pioneering hot rodders. According their literature, the Bootlegger grind is said to be the most powerful series of street performance cams ever produced by Lunati. Designed to out-perform the already powerful Voodoo cams, the Bootlegger series combined even faster opening with controlled closing ramp rates to further increase area under the lift curve. These lobes were then configured with a tight 108-degree lobe separation angle (LSA) and a 104-degree intake centerline. This combination netted not only impressive performance but a sound quality that let everyone know your motor means business. Thanks to a thoroughly modern cam profile, the Bootlegger cam series offered all the attitude with plenty of low- and mid-range power, not to mention daily drivability. That every Bootlegger came shipped in a wood-look cam box (just like back in the day) was just icing on the cool cake.
So far everything looked and sounded great on paper, but there was only one way to really test the new Bootlegger cams, we had to install one in an engine. As luck would have it, we had a perfect candidate in the form of a GMPP 383 crate motor, or more specifically a 383 short block. Designed as a hot rod power plant destined for street use, the 383 was just begging for the right performance cam. It is (almost) always possible to add power with wilder cam timing, but the key to any successful build is to install not the biggest, but rather the best camshaft for your given application.
Huge power numbers are possible with a race-only 383 stroker using the right combination of components (including the camshaft), but we were looking for something different with this 383 short block. Given its daily driver status, we went for a more streetable combination and this included our cam choice. What we wanted was a cam that offered more power and drivability but still rumbled like the Duntov 30-30 of yesteryear.
Since our street/strip 383 was skewed toward the street side of the equation, we chose the cam accordingly. For small block Chevys (also offered for BBC and SBF), the new Bootlegger cams were offered in hydraulic flat-tappet, retro-ft and standard hydraulic roller configurations. Since our 383 was equipped to accept a hydraulic roller stick, we chose the Lunati part number XXX12224HRK. This complete kit included not only the cam, but the hydraulic roller lifters, timing chain and even a valve spring upgrade for use with the high-lift, hydraulic-roller cam profile.
The Bootlegger cam offered .554 lift (both intake and exhaust), a 224/236-degree duration split and afore-mentioned 108-degree LSA. The mild intake duration specs and 12-degree duration split between intake and exhaust joined forces with the tight LSA to offer the ideal combination of power, drivability and aggressive sound quality. The Bootlegger cam and supplied hydraulic roller lifters were installed along with the double roller timing chain. Additional valve train components included a set of aluminum roller rockers and hardened pushrods.
With our Bootlegger short block ready to run some shine, it was time to complete the motor and officially make some noise. Topping the 383 was a set of Holley aluminum heads, Weiand Street Dominator intake and Holley 650 Ultra Street Hp carb. The components were chosen to work well with the new cam profile. The flow rate of the heads and dual-plane intake were designed to optimize power production up to 6,000 rpm, making them ideally suited for use on the Bootlegger 383. We finished off the motor with an MSD billet distributor and set of 1 ¾-inch dyno headers.
Before installing the distributor, we filled the pan with 5 quarts of 30W Driven (break-in) oil and primed the system to ensure oil supply to all the lifters and rockers. We then performed a final lash adjustment (1/4-1/2 turn preload) and proceeded with our computer-controlled break-in procedures. After dialing in the jetting and timing (34 degrees), we were rewarded with peak numbers of 439 hp at 5,800 rpm and 469 lb-ft of torque at 4,100. Torque production exceeded 450 lb-ft from 3,300 rpm to 4,800 rpm, making for one sweet torque curve. The impressive power was combined with zippy throttle response and a healthy idle quality that let everyone know the driver of this Bootlegger 383 might just be sporting a little junk in the trunk.
Spark intensity isn’t something a lot of people pay attention to — but they should. Feeding the coil with 14 volts instead of 7 automatically improves spark intensity, improving throttle response, fuel mileage, and maybe even adding a bit more power, too.
Words and Photos by Jeff Smith
Schematic by Eric Rosendahl
Performance car guys are all about making good cars better. The average person thinks anything from the factory is automatically the best it can be, but real car people know new technology usually means improvement.
A case study can be made with Ford and Mopar electronic ignition boxes from the ’70s. Honest Ford guys will admit that the Duraspark system has not lived up to its name, and replacement boxes are even less reliable. While original factory Mopar ignition boxes are good, the design for both the Ford and Mopar boxes suffers from an often overlooked, yet crucial design consideration.
A magnetic pickup creates a signal when the rotating pole piece on the distributor shaft crosses the fixed magnet. This generates a tiny signal that triggers the coil — essentially an electronic version of a set of mechanical points, except no voltage passes through the pickup like it does with ignition points.
The typical response on many forums to questions about these factory ignitions is the simplistic: “Just stick an MSD on it!” While that’s one solution, this skips over a fundamental approach to hot rodding — using good factory parts for a performance application.
Before we get into the details of how easy it is to adapt an HEI module to a Ford or Mopar magnetic distributor, we have to put this whole brand loyalty thing on the table. We can already hear the Mopar guys screaming, “Install a GM part on my Mopar — over my dead body!” For those who share that sentiment, save the trouble of addressing those poison emails to this author; this story is clearly not for you. But for the rest of the performance world who is open-minded enough to learn something new and to whom performance efficiency is more important than blind brand loyalty, please follow along.
First, let’s address the weakness in the Ford and Mopar ignition systems. If we look closely at a wiring schematic of either system, both include either a resistor wire (Ford) or a ballast resistor (Mopar) that limits the voltage to the positive side of the coil. This is done to limit the amount of voltage fed to the coil to prevent it from overheating at low engine speeds.
This is a Ford DuraSpark distributor our buddy, Tim Moore, pulled out of the junkyard. He eliminated the vacuum advance can and filled in the hole to make it appear more like a mid-’60s Ford dual point distributor. He has converted the wiring to a two-pin connector as used on an MSD distributor. We can now use this distributor to trigger an HEI module.
The main reason for the resistor is because the original coils used with these ignitions were the oil-filled canister design with high internal resistance. The resistor circuit can often be the cause of a loss of ignition performance if, after decades of use, the resistance in the circuit increases, even further reducing the voltage fed to the coil. Bone stock, these systems delivered around 6 to7 volts to the positive side of the coil. Less voltage in means less power delivered to the spark plugs.
This is an HEI large cap distributor, and you can clearly see the blue four-pin module bolted in place. This module can be easily adapted to any magnetic pickup distributor, like either a Ford or Mopar version.
When GM designed the high energy ignition (HEI), engineers combined the electronic module with a completely new design coil called an E-core or laminated core coil. The E-core cools the windings more efficiently because the coils are exposed to the air. This allows the coil designer to reduce the coil’s internal resistance. Old-school oil-filled coils typically measure 1.0 to 1.5 ohms of primary circuit resistance. E-core coils operate with as little at 0.30 ohms. With less resistance, the coils can accept a higher feed voltage and generate more secondary spark energy and higher spark plug gap voltage, creating a more powerful ignition system.
The HEI module is designed to supply the E-core coil with the full-system voltage of generally 14.0 to 14.5 volts. The Ford or Mopar electronic boxes are limited with either a resistor wire or large ballast resistor that limits the voltage to the primary side of the coil to around 7.0 to 7.5 volts. It should be obvious which system will perform more efficiently.
Now that we have some actual facts to support this concept, it might become clear why the HEI module would be the equivalent of bolting in a high-performance ignition system on even a stock Mopar Slant 6. This is not new technology; several ignition companies offer HEI-style distributors for Ford and Mopar engine applications. While there’s nothing wrong with this approach, the conversion requires replacing the original distributor. But if you have a Ford or Mopar magnetic pickup distributor, you already have the correct distributor for a conversion.
Here are two performance HEI modules. Note we’ve spread a white thermal transfer paste on the backside of this module. This will aid in managing the heat created by the module. Do not use MSD Spark Guard. That material is actually an insulator, which will contribute to overheating and failing the module, so don’t make that mistake. We’ve listed a couple of sources for thermal transfer paste in the Parts List.
But first, we need to know a little bit more about magnetic pickups. The process is pretty simple. The distributor shaft is equipped with eight (for a V-8 application) pole pieces or lugs that rotate with the shaft. The pickup contains a magnet that creates a tiny signal every time a lug passes across the pickup. This system essentially replaces the old points system with a more reliable switching mechanism. Every time the pole piece triggers the magnetic pickup, it sends a signal to fire the coil then eventually finds its way to the spark plug.
So, now that you have a grasp on the technology, let’s look at how to adapt it to a typical electronic-style distributor. The early Ford DuraSpark I and II and Mopar electronic distributors employ a magnetic pickup much like the GM HEI. The only critical information you need is to determine which wire on the magnetic pickup is the trigger wire and which is the ground.
For the early Ford two-wire distributors, the orange wire is the signal wire (+) that connects to the “W” terminal on the HEI module, while the brown wire is ground (-) that connects to the HEI “G” terminal. Later, DuraSpark versions came with three wires, with the third black wire as an additional ground. In this three-wire version, orange is the signal wire (+), while the violet or purple is ground (-). Mopar distributors use a black wire for the ground side (-), while the orange wire is the signal (+) connection. It’s that simple.
This schematic shows the connections necessary to wire up the HEI module to any magnetic pickup distributor. Note the distributor we’re using has three wires exiting the distributor. The third black wire is a ground. While the wire colors from the magnetic pickup will be different, they all wire up the same way.
We’ve created a schematic that reveals just how simple the wiring is for an HEI module. In this illustration, we show a third wire exiting the distributor, like the later Ford versions. The colors coming from the distributor will also change based on the original manufacturer, but otherwise, the information doesn’t change. The “W” terminal on the left side of the HEI module is the signal connection, while the “G” terminal is the ground.
On the power side of the module, the “B” terminal always connects to the switched power or battery (+) of the coil, while the “C” terminal goes to the negative (-) side of the coil. With those four simple connections, plus adding a ground between the module, mounting base, and the engine and battery, will produce a functioning ignition system.
We mounted our HEI module on a 1/8-inch thick aluminum plate and added a wiring terminal strip just for grins, but this could be easily eliminated. We also found a cool, affordable aluminum bracket offered by Deisgned2drive.com that mounts the HEI module underneath the Mopar distributor.
We mounted an HEI module to an aluminum plate and also added a wiring terminal strip, but that could easily be eliminated, as it isn’t necessary.
To add a little more fun to this idea, consider that the magnetic pickup used in these Ford and Mopar distributors is the same style pickup employed in MSD distributors. So, this makes it really easy to convert an existing Ford or Mopar distributor to use a FAST, MSD, Pertronix, or any other company’s capacitive discharge (CD) style ignition system. In fact, MSD makes a slick wiring adapter to convert your distributor to the small, two-pin MSD connector. Then, even with a CD ignition in the car, you can also keep that small aluminum HEI module plate as a backup. That way if the MSD box fails, it would only require a few simple wiring connections to hook up the HEI module.
We rigged a simple bench test to show how this idea works with a Ford distributor. We wired the HEI module and coil according to the schematic, grounded the steel plate, the HEI mounting plate, and the distributor all to a 12-volt battery, and spun the distributor to create a hot spark right off the coil wire.
Hopefully, we’ve given you some ideas on how to upgrade a Ford or Mopar ignition to something a little more powerful at an extremely low cost. Sometimes, good ideas can also turn out to be the least expensive.
Valvetrain prep, on the surface, would appear to be a fairly straightforward topic. You pick the right parts as described by the guy on the tech line, check the specs on the parts when they arrive, degree the camshaft, and away you go. But, the reality of picking parts and setting them up correctly to get the best performance and durability is not always as easy as it may seem.
We sat down with two of the top valvetrain engineers in the business, Billy Godbold from COMP Cams and Jerry Clay from Crane Cams, and asked some questions commonly misunderstood by engine builders and enthusiasts. Most interesting to us as we assembled this story was we found the “easy” questions were not so easy and packed to the valve covers with surprisingly new information. Read through the following, and we bet you’ll learn something along the way. We certainly did.
How do I set hydraulic pre-load?
Godbold: The best method is to have a dial indicator on the back of the rocker above the pushrod as you tighten down a non-adjustable rocker or set the preload on a stud mounted rocker. In this way, you can determine the real preload amount without having to think about turns per inch or how much the ratio changes the pushrod movement when you turn a bolt in the trunnion.
For the record, a quarter turn is about 0.010 to 0.013 inch, and a half turn is about 0.020 to 0.025 inch of trunnion movement, but the pushrod preload would be about 50 percent more at that end, due to the fixed valve tip position and rocker ratio. I like about 0.020 inch preload in most applications, but you can measure it much more closely with the dial indicator.
However, counting the turns from the point where the pushrod begins to load to the lifter piston bottoms out is also very good. Using this technique, you know the total adjustment range and can choose between the standard performance light setting (1/4 turn down), the typical OEM setting of mid-travel, or go to a longer pushrod and run it close to the bottom to minimize oil volume (and, thereby, oil bubbles) by setting the preload three-quarters of the way to the bottom.
As you might have guessed, degreeing the camshaft is critical to achieving peak engine power and torque. But if you use lobe centerline when determining camshaft position, you could be doing it wrong!
What is the most common mistake you find with engine builders these days?
Clay: The challenge of getting the camshaft degreed properly is well documented, and the downside of not setting up the camshaft correctly should be motivation enough to spend the time required to get it right. But complicating the camshaft degreeing process these days is understanding that camshaft lobes are not symmetric. Translation: The opening and closing ramps are not the same. As such, determining the centerline of the lobe is far more difficult. If you are degreeing your camshaft by noting the centerline of the camshaft, you could be a half to a full degree off. For that reason, you should always degree your camshaft at 0.050-inch lift. All camshafts come with this spec, so there is no reason to ever use centerline measurements again.
Full-travel or short-travel lifters — how do I know what is best for me?
Godbold: Assuming you read the preload description in the first question above, you will note there are good reasons to choose light, mid, or deep preload settings. Knowing there are benefits to being 0.025 inch from the top, in the middle, or 0.025 inch from the bottom, you can quickly deduce why a short-travel lifter can put you in all of those positions at the same time. The negative is you either are required to run a very specific pushrod length or an adjustable rocker system.
Short-travel lifters will always outperform the full-travel lifters, but in many applications, the slight improvement in performance may not outweigh the time and cost to get the preload so close. On the full-travel lifters, you have over 0.100-inch range of preloads, and anything from 0.020 to 0.080 inch preload will perform more than adequately for most applications.
When building an engine, what are the critical dynamics to consider when selecting valvetrain components?
Godbold: Component mass, stiffness, and natural frequency are the three main focus elements in valvetrain component design. While looking at these parameters at the component level, we must also consider how the entire System Effective Mass and System Stiffness will respond to changes at the component level. Also, the driving frequencies (from the cam profile) need to be considered. Going to a very good, but heavy rocker on a light system can be a bad choice, even with an excellent component. Looking at the systems approach is paramount for good dynamics.
How does compression ratio affect camshaft selection?
Clay: The key factor to consider here is cylinder pressure. If you have a lower compression motor, say 9.5:1, and you use a camshaft that is fairly large (increased overlap between lobes, which allows both the intake and exhaust valves to be open at the same time), then you will bleed off cylinder pressure, which equates to reduced horsepower and torque output.
On the other hand, if you’re running a high compression race motor and your camshaft has a minimal amount of overlap, the cylinder pressures can go sky high. This is far less of a problem for race engines than it is for street-bound power plants, but it should be considered and factored in at the time you choose your cam. In addition, the type of cylinder heads you’re using and the quality of available fuel should be taken into consideration. If you have to stick with pump gas, the rule of thumb is to limit compression to 10:1 with cast iron heads and 11:1 compression with aluminum heads.
I’ve had issues with bronze distributor gears in the past wearing down quickly, causing some serious ignition timing issues. What is a Melonized gear, and is it right for my small-block Chevy application?
Godbold: As most engine builder have experienced, compatibility between the distributor gear materials and the distributor drive gear on the camshaft can be an issue that can wipe out an engine if the wrong parts are selected. Melonizing was originally developed by General Motors and Ford to harden the surface of the metal through a form of nitriding and, most importantly, works great as a universal distributor gear for any camshaft application. With Melonizing, microscopic nitrogen and carbon “needles” are driven into the surface of the metal, increasing its surface hardness. The result is a lower co-efficient of friction, enhanced lubricity, and corrosion resistance.
With distributor gears, Melonizing hardens the metal, making it much less prone to wear as opposed to a bronze gear, which is not compatible with all camshaft gears. Melonized gears are available for the big three engine platforms — GM, Ford, and Chrysler — and provide amazing durability. As an added bonus, by virtue of the fact there is less distributor gear wear, more accurate ignition timing with far less spark scatter is also achieved.
What is your most popular camshaft for muscle car engine builders?
Clay: Actually, Crane has been the manufacturer of record for original blueprinted factory camshafts for a number of years. So, if you want that Duntov 30-30 camshaft, we have the original spec camshaft ready to go. We found that there were a number of customers who wanted to put their vehicles back to the original restored condition, right down to the engine internals. Nothing cries perfect restoration better than that factory thump from an original muscle car. We currently offer a long line of original engine cams for Z/28, L88, LS6, and other popular Chevy muscle cars, along with Ford big- and small-block engines, Boss 302, Boss 429, and many Mopars, from Hemis down to 340c.i. small blocks. No one has a better or more exacting replica camshafts of the factory OEM offerings.
Goldbold: COMP Cams offers a number of exact reproduction grinds made from the original OEM prints and specs. One thing that caught our attention was how well those sold even though everyone knew they might be 50-plus hp down compared to a more modern camshaft design.
Melonized distributor gears deliver long life and accurate ignition time, while avoiding the issues commonly found with excessive brass gear wear.
We started to ask our customers exactly why they wanted the reproduction cams, and their answers fell into two major categories: exact reproductions of the factory grinds or exact replication of that classic muscle car sound. For those customers looking for exact reproductions of the factory part, we already offer the perfect replacement. However, for probably the majority of customers requesting a nostalgia camshaft, they remembered a certain sound from their childhood or early years and wanted improved performance, but not at the cost of losing any of that ‘60s and ‘70 ‘personality.’
For those customers looking for that classic camshaft sound, we designed a new series of hydraulic and solid flat tappet profiles called the New Nostalgia Plus family. These profiles are slightly slower off the seat than the Xtreme Energy profiles, but have excellent area under the curve for outstanding power. The funny side effect was we started to think, ‘what if we took this a step further?’ The New Nostalgia Plus family probably helped get COMP even more excited about the sound and character of camshaft, and possibly initiated our testing of what would become the Thumpr series of camshafts, which is far more popular than either the Nostalgia or New Nostalgia Plus camshaft line.
Ask any engine builder their choice for the best combination of rotating parts when building an engine and you will get a wide range of responses. After all, there are a huge number of component choices. Often, the builder’s own personal experiences, along with which parts provide the best profit for them (remember, those guys need to make money too!), will dramatically affect their answers.
If there is one consistent answer across the board, however, it is “matched” systems deliver greater longevity and better performance than selecting individual pieces that may not be completely compatible. In their quest to improve customer service and boost performance, manufacturers of aftermarket performance auto parts have made it much easier to purchase the required parts and ensure nothing is left out of the equation.
So, the question remains; how do you pick the right “system” for your engine build? To get some answers, we spoke with Lunati’s Kirk Peters and Justin Bowers to get some insight into the questions that should be asked when shopping for a rotating assembly. Though they speak about Lunati’s products, most manufacturers have different levels of offerings, so the questions should still be asked regardless of manufacturer. Here are their Top 5:
What is your budget and is that realistic?
Lunati’s Signature Series and I-beam rods are designed with the all-out drag race car in mind. Cars with power adders such as blowers, superchargers, turbochargers, and nitrous especially need added strength in the bottom end.
Bowers: Lunati’s rotating assemblies, which include a crankshaft, rods, pistons, pins, rings, and bearings, range in price from around $2,500 to $4,900. This is the best option when building an engine, since each part has been selected and tuned to achieve a certain amount of power. For this price range, they are getting a heck of a lot of technology along with parts that deliver excellent quality.
Peters: In addition, upgrading only one item in a matched system can deliver a false sense of reality, and a letdown in terms of performance expectation.
What is the desired horsepower expected from your engine?
Peters: Someone building a 550-hp versus 1,300-hp engine is going to have different requirements. In the first case, a Lunati Voodoo assembly rated for up to 1,000 hp would suffice, while the recommendation for the latter is a step up to the premium Signature Series assembly rated for 1,500+ hp. The Voodoo assembly is a great choice for street/strip applications where higher-than-OEM durability and strength is needed, but other engine upgrades have been limited so the car is still streetable. The Voodoo assembly with 4.00-inch stroke for LS engines is Lunati’s biggest seller and a hit among drag racers.
Bowers: The 4340 non-twist forged Voodoo crankshaft is nitride heat-treated and features micro-polished journals with lightening holes to reduce weight for faster acceleration. It’s packaged with Lunati’s H-beam rods — also made from forged 4340 steel — ICON forged pistons, pins, and rings, and King or Clevite premium engine bearings.
Will you be using power adders?
Lunati’s Signature Series crankshaft features gun-drilled mains, lightened and micro-polished rod journals, and windage-reducing, contoured wing counterweights.
Peters: Power adders such as blowers, superchargers, turbochargers, and nitrous put additional stress on an engine’s bottom-end, making a durable rotating assembly essential.
Bowers: Both the Voodoo and Signature Series cranks are forged 4340 steel, but the Signature Series features a beefier forging that is designed to withstand the extra demands. The Signature Series crankshaft features gun-drilled mains, lightened and micro-polished rod journals, and windage-reducing, contoured-wing counterweights. It is also pulsed-plasma nitride heat-treated for even more strength to hold up in all-out racing applications. Included in the Signature Series assembly are premium Diamond or Mahle brand forged pistons, pins, and rings, premium King or Clevite engine bearings, and your choice of Lunati’s H-beam or I-beam rods. The difference between the offered rods is primarily that the I-beam version is CNC-machined and undergoes additional testing for impurities and defects.
What is your application?
Peters: Different types of racing require different components, lightweight versus standard weight. Though all racers look to reduce weight in favor of faster ETs, going the lightweight route in drag racing can be tricky. You could be walking the line between more power to get you down the track and too much power for the bottom end to support.
Bowers: Lunati’s new Voodoo Lightweight Crankshafts, which can be custom-packaged into a balanced assembly, could be a viable option for some heads-up, naturally aspirated classes and bracket racers. Obviously, budget and horsepower requirements will affect that decision.
Are all the parts matched at the same horsepower?
Peters: It is not a good idea to upgrade the bottom end one component at a time. Likewise, they say mismatching components in terms of their horsepower rating, can not only affect performance, but hurt the pocket book down the road. As an example of that concept, we have seen folks use a cast crankshaft upgrade with a set of steel H-beam rods. That would only give you the lesser horsepower rating that matches the crankshaft, not the rods.
Bowers: One thing I could see being an issue is if a guy purchases a good crank then goes cheap on rods and pistons. Well, then he breaks a set of $100 rods and takes out a $1,000 crankshaft. I would suggest it’s better to save up and purchase matching parts.
Q & A: Five things to know before you install a supercharger system
Words: Bertie S. Brown; Photos: Torqstorm
Superchargers require different care and handling than normally aspirated engines. For one, they live in a pressure-packed world where external environments have little to do with their ability to intake, compress, and kick out fuel and air. TorqStorm Product Manager Rick Lewis and Rob Walden of LWA Engines know what it takes to achieve proper supercharger operation. Here are some of the most misunderstood things when it comes to generating the most power from your supercharger.
What camshaft spec is best?
Installing a camshaft designed specifically for a supercharged engine is best. But, often the existing camshaft works surprisingly well, and those with lobe separation angles between 112 to 116 degrees are ideal. Of course, when cruising down the road, and thus not building boost, nothing more than a normal camshaft is required. However, to realize maximum power with narrow lobe separation angles, there is a sound argument for installing a more suitable cam.
“Your aim is to trap as much boost in the cylinder as possible,” says Rob Walden of LWA, an Atlanta tuning house. “The success or failure in achieving this is affected by the camshaft’s lobe separation angles and valve overlap. Too much overlap and you’ll blow your boost out the exhaust.”
In general, naturally aspirated engines run narrower lobe separation angles of around 106 to 108, whereas supercharged, turbo, or nitrous engines operate with 112 to 114 and higher. On larger displacement supercharger units, 116 to 118 degrees of separation are common.
Compression ratios and intercoolers
“The compression ratio for pump-gas engines is crucial,” Lewis says. “TorqStorm recommends ratios of 9.1 to 9.5:1.” Higher ratios usually require an intercooler.
“But if you are running less than 12 psi of boost and under 10:1 compression ratio with a blow-through carburetor or venturi-style throttle body fuel injection, you do not need to run an intercooler, even on pump gas,” he continues. “Blow-through carburetors do a very good job of controlling intake charge temps.”
What increases in power can I expect?
“Our single centrifugal supercharger, which supports 700-plus hp and generates boost of 6-8 psi, increases engine power by about 40 percent over stock performance,” Lewis claims. “Add a second unit which collectively generates 12-15 psi and the engine’s power output potentially doubles.”
Note that the fuel pump must support 21 psi of fuel pressure, and it requires a return line to the tank.
Carburetors and regulators
The fuel delivered to a carburetor on a normally aspirated engine operates at 6 or 7 psi. But the blow-through carburetor is designed to operate from 5 psi to boosted pressures up to 18 psi on a forced-induction engine. This task is achieved by the introduction of a boost-referenced fuel pressure regulator.
The fuel delivered to a carburetor on a normally aspirated engine operates at 6 or 7 psi. But the blow-through carburetor is designed to operate from 5 psi to boosted pressures up to 18 psi on a forced-induction engine. This task is achieved by the introduction of a boost-referenced fuel pressure regulator.
Through a small-bore hose, the regulator is connected to a port on the intake manifold below the carburetor throttle plates. In this way, it reads boost and increases the fuel pressure by 1 psi for each additional 1 psi of boost. Blow-through carburetors also possess more robust floats to deter crushing under pressure. In addition, their jetting is different, and they operate with sealed throttle shafts to prevent leaking under pressure.
EFI, injectors, pumps, and tuning
A large number of supercharger kits, especially when using EFI induction, are installed by specialty shops that use a chassis dynamometer and a laptop computer to obtain the correct tune.
“So most tuning would be conducted by someone with the expertise and a chassis dynamometer,” Walden, who uses HP Tuners software, says.
On all late-model EFI vehicles, TorqStorm offers their superchargers as Tuner Kits only, which means they don’t include ECU or fuel management.
Correct belt tension is critical to maximizing power output. Belt slippage is the biggest killer of boost.
“Often, an EFI supercharger kit does require an upgraded fuel pump or a booster pump,” Walden says.
Booster pumps increase their fuel delivery by increasing their voltage output — higher voltage spins the pump faster. Also, they are boost-referenced, which means that as the boost increases, so too does the fuel pump pressure. Thus, the pump’s volume keeps pace with the demand at a corresponding rate. Alternatively, should greater delivery be required, a larger in-tank pump could suffice.
Fuel injector sizes are determined by the engine’s power output. They are calculated in pounds per hour of fuel dispersed. For example, 25 lbs/hr is sufficient to support 350 hp, 45 lbs /hr is sufficient for 500 hp, and so on.
Lastly, hot air expands and cold air condenses — the colder the air, the better the cylinder-filling, to say nothing of its deterrent to detonation. Thus, adding an intercooler when costs permit is never wasteful.
Bonus explanation: Clearances
Clearance questions around the alternator and above the carburetor seem to be the chief concerns.
“We provide chassis drawings,” Lewis says. “With regard to alternator relocation on the small-block Ford and big-block Mopar — both A-body and B-body — we have mocked up all those components and, though the clearances appear to be close to the engine, they are adequate.”
Nevertheless, the most prominent clearance question involves the carburetor hat. TorqStorm’s previous “two-can-style” hat measured 3.5 inches deep. Their latest free-flowing innovation, however, measures 3.25 inches. Though usually regarded as more restrictive, low-rise carburetor hats, measuring 2.400 inches are still available.
Painless Performance is well known for complete wiring solutions. Their Trunk Mount Battery Cable system and Grounding Strap kit are the best way to make certain all vehicle systems operate correctly. For classic muscle cars with late model drivetrains, these two products help protect against errant static (or direct) current electricity that can kill highly sensitive ECMs.
Features
Twin 16-foot #1 cables
Heavy Duty terminal
(1) Large 1/0 Gauge Engine strap
(3) 10 Gauge Body Straps
In The Field
On our 1971 Camaro, the cables were easily fed from the trunk, through the rocker cover plates, and into the engine compartment. We had more than enough cable for the job.
The Engine Ground strap was mounted from the bellhousing to the frame, while this body strap connects the core support to the frame. Removing the paint at the connection point is critical.
Terminals are already installed on the cables, eliminating the need to do it yourself as found with most custom battery cables.
Cam Says:
These high-quality parts are easy to install in a minimal amount of time. Instructions can be found online — if you need them.
Things to know about fluids before you pour them in your transmission
Words: Cam Benty
The world of transmissions has greatly evolved since the days of the classic muscle cars, when you simply flowed in some random ATF and set out for parts unknown. Today, not only are the transmissions far more complex, the fluids used to keep them “well oiled” are highly sophisticated.
We recently had a chance to speak with Lake Speed Jr. from Driven Racing Oil about transmission fluids for both automatic and manual transmission vehicles. While the advertising hype will often tout the benefits of various products based on limited use of the facts, we hope you will find this information extremely helpful next time you think about filling your transmission.
Here are some critical questions every performance automatic and manual transmission owner should know and fully understand.
What is the difference between old school and current automatic transmission fluids?
Some fluids are vastly different. For example, a modern Dexron VI fluid features a different viscosity and co-efficient of friction compared to an old-school Ford Type F. These two fluids are completely incompatible. The fluid required to run a modern 8- or 9-speed automatic utilizes different chemistry than what is needed to run an old-school 3- or 4-speed automatic.
What should late model transmission owners know concerning internal wear with electronic transmissions?
The biggest issue with fluids and electronic transmissions relates to seals and wiring. Some fluids can soften and degrade seals, as well as the plastic wire covering. If the seals fail, so will the transmission in due time. If the wiring shrouds fail, all kinds of bad things can happen.
How can vehicle owners increase the longevity of these sophisticated transmissions (manual or automatic)?
There are several ways to accomplish this. First, by designing the fluid to be part of the transmission, the longevity and performance of the transmission can be enhanced. Second, by not restricting the performance of the transmission to the lowest price multi-vehicle ATF at the parts store, OEMs are unlocking the benefits of higher quality base oils. For example, a high-quality, full-synthetic Dexron VI will last longer and protect better than a conventional multi-vehicle ATF.
What about “yellow” metals found in manual transmissions? Is there anything special about their care?
Old-school manual transmissions with yellow metal synchronizers must run fluids compatible with yellow metals. If you use the wrong fluid, the synchronizers will not properly function and can be badly damaged. If you are unclear as to what the right fluid is, you can call our tech line for more information, we’re happy to help.
Young vs. Old Transmission Science
Beyond the fact that both the old-school Turbo 400 and modern Dual Clutch can officially be defined as transmissions, they have little in common. One transmission is an automatic, and the other is an automated manual transmission, but the differences go beyond just the mechanics.
The fluids for these transmissions are also very different. The increased use of application-specific transmission fluids led Driven Racing Oil to develop a new line of its own to meet these specialized needs.
For the old-school transmissions, Driven now offers AT3 for automatic transmissions that require Dex/Merc III ATF and the new 80W-90 GL-4 gear oil for manual transmissions with yellow metal (brass or bronze) synchro rings. Both “old-school” fluids combine modern technology and proven additive systems to provide the best protection and performance for the old-school applications.
For modern transmissions, Driven offers an even wider selection of products to meet the increased complexity of modern vehicles. AT6 surpasses the GM DEXRON IV specifications, and Driven’s 75W-90 GL-5 gear oil is compatible with straight-cut transmission gears, limited slip differentials, and hypoid gear sets.
Not only are all of the new Driven products compatible with these applications, they are also track tested and performance proven for use in both street and track environments.
In the end, the key to increased performance and longevity is utilizing the proper fluid for the application. The new offerings from Driven provide the performance and longevity you need by nailing the needs of each specific application — old school powerglide or modern T56.
Our ’66 Chevy pickup had come back from the dead, smoothed and shaped to original configuration and was now ready for a fresh paint. We knew we wanted to stay with the same color, but the remaining question was whether to use waterborne or solvent-based paint.
Waterborne paints have been around for a decade or so, but today are all the buzz. For those who have come to know waterborne from personal experience, they have learned what it takes to achieve success. For those who have not sprayed with water, it is an unknown that makes them uneasy about the results they will encounter. As with anything, it’s simply a matter of having the right tools for the job and knowing what to do.
Currently, waterborne paint is limited to the pigment layer of the painting process; the primer and clear coats still retain the solvent-based chemical and are used with equipment we all know and love. Applying waterborne paints requires a host of ancillary tools and techniques to achieve a smooth, run-free final appearance. A changeover is not simple, but clearly (and luckily) from those painters we’ve polled, waterborne paints perform well with excellent final results.
As with anytime new paints or equipment are used, we suggest practicing on some random, non-important surface until you achieve some competency. Waterborne paint is different from solvent-based paint — different mixing techniques and spray guns, and those mysterious dryers required for proper laying out of the paint.
When working with waterborne paint, make certain you are protected from toxic fumes and materials. It is critical to frequently change out air respirator canisters in your breathing apparatus and dust off that full-body, paint protective suit.
Follow along as we show you the basics and beyond of waterborne paint application.
Rather than the usual V-8, we ran this cam test on a…….
By Richard Holdener
The usual situation is we find some unsuspecting V-8, either from the local Pic-a-Part or something we gathered together the necessary parts to build, then test a ton of performance parts. This works well, but the problem with such an approach is that man does not live by V8s alone.
Contrary to popular belief, manufacturers offered vehicles with engine combinations offering less than eight cylinders. Case in point, Chevy sold literally a ton with V6 power, both as a base engine with V-8 options and as the top of the line in applications like the S-10 truck, Blazer, and Astro van. Simply that the engine existed was reason enough to want to improve the power output, but that the 4.3L V-6 was produced in such numbers merely cemented the decision. Toss in the fact the little V-6 was essentially a small-block Chevy missing a pair of cylinders and you have what’s called a moral imperative.
The question now isn’t so much should we upgrade the little V-6, but what should be our first step? Obviously, we first had to choose a suitable candidate, after all, the 4.3L was produced for nearly 30 years, from 1985-2013. Available in a variety of different configurations and factory power ratings, we chose a 2002 version that offered a number of desirable features, including a balance shaft, free-flowing Vortec heads, and even factory roller rockers, similar in configuration to those on the LS V-8 engine family.
Our thinking was that if we were going to keep most of the motor stock, why not get the best stock parts we could. The Vortec heads offered the best flow of any of the factory offerings, and we liked the fact the balance shaft combo greatly reduced the vibrations inherent in a V-6 configuration. Though the 2002 model was offered in fuel-injected form, we chose to run it with more user-friendly carburetion.
Prior to testing, the 2002 4.3L V-6 was rebuilt to ensure it was up to the stress of the dyno. Though we’ve had great success with our many junkyard adventures, we wanted to give this V-6 a new lease on life. It was rebuilt with fresh rings, bearings, and gaskets from Fel Pro, but the 3/4 small block also received a .030 over bore and a new set of replacement pistons. The Vortec heads were also given the once over, with a valve job, surface, and new seals before we installed a set of 26915 (beehive) spring upgrade from COMP Cams.
Some enthusiasts fear the complexity of the balance-shaft motors, but assembly was no more difficult than lining up the dots on the factory timing chain. The one area we feel we missed out on was the exhaust, as the lack of available V-6 headers (from our usual sources) led us to retain the factory cast-iron exhaust manifolds in testing. Long-tube headers would certainly unearth additional power, but our cam test was run with the stock stuff.
The long block was all but stock, including the stock hydraulic roller cam, but as indicated previously, we did make changes to the induction system. Off came the problematic factory fuel injection, replaced by a simple, but effective, four-barrel carburetor. Edelbrock supplied both the four-barrel Performer intake designed specifically for the revised intake bolt pattern employed on the Vortech heads, as well as a matching 500 cfm Thunder Series carburetor.
To run the carbureted induction system, we also swapped out the computer-controller distributor for an MSD unit. The billet distributor was run in conjunction with a 6AL ignition amplifier. The one problem we encountered while testing was the outer portion of the factory damper spun itself off the inner during one of the dyno pulls. We replaced the stock V-6 damper with a neutral-balance V-8 damper from Speedmaster.
Run on the dyno with the new COMP cam, the power output soared to 251 hp at 5,200 rpm and 298 lb-ft of torque at 3,500 rpm.
Though we had everything needed to make our little V-6 run on the dyno, we didn’t yet have the ability to significantly improve the power output. The missing link in our performance chain was a new cam profile, but first we had to run the freshly rebuilt motor with the stock cam. After a few break-in cycles, the carbureted 4.3L V-6 responded with peak numbers of 207 hp at 4,700 rpm and 287 lb-ft of torque at 2,800 rpm, though we suspect this torque number was an anomaly, as it occurred at the initial load-in point. Regardless, the V6 was happy, if not powerful with the mild stock cam.
4.3L V6 Cam Test-Stock vs COMP 280HR It is pretty obvious from the dyno results that the 4.3L V-6 was desperately missing the right camshaft. Run with the Edelbrock intake, carb combo, and stock cam, the 4.3L produced 207 hp at 4,700 rpm and 287 lb-ft at 2,800 rpm. After installation of the 280HR cam from COMP Cams, the power output jumped significantly to 251 hp at 5,200 rpm and 298 lb-ft at 3,500 rpm.
To improve the situation, we installed a 280HR grind from COMP Cams design for the later balance-shaft motors. The 280HR offered .525 lift, 224 degrees of duration, and a 110-degree lsa. Equipped with the new COMP cam, the power output of the V-6 jumped to 251 hp at 5,200 rpm and 298 lb-ft of torque at 3,500 rpm. Forty four horsepower (peak to peak) is an impressive amount, but even more so when you look at it as a percentage of the original 207 hp (more than 21 percent). I guess the missing link in this 4.3L was a real camshaft!
Bolting on the right set of heads can make or break your stroker Ford.
Words and Photos By Richard Holdener
The list of things that change the power output of any motor is endless. Check out Facebook, the forums, or any gathering of gear heads and you’ll find any number of esoteric discussion topics, ranging from merge collectors to rod ratio. Everyone has their favorite power adder, tenacious tune, or top-secret cam profile, but the truth is, the success of any combination is determined by its compatibility.
Ford fanatics may argue the point, but their wonder Windsor (like all lesser motors), is nothing more than a glorified air pump. Once we come to grips with that fact, we immediately recognize the power output of said pump is a function of the amount of air it can process. The word process is important here, as air through (into and out of) the motor is decidedly different than simply measuring the airflow potential of cylinder heads or an intake manifold. Getting the Windsor pump to process that air effectively requires all the individual components working in harmony. This occurs when all of them are designed to operate effectively over the same rpm range.
Don’t get us wrong, things like rod ratio, collector design, and the air/fuel curve all play a part in power production. They just take a back seat to the three major contributors, namely the heads, cam, and intake, or big three as we like to call them. The big three determine not only the peak power and torque outputs, but the overall shape of the power curves, from idle right through to the redline. This test, on the 210cc heads from ProMaxx, was designed to illustrate what happens when you miss on just one of the big three.
COMP Cams also stepped up with a double-roller timing chain, retro-fit hydraulic roller lifters, and hardened pushrods. Note the ARP damper bolt used to secure our neutral Speedmaster damper.
We previously ran these ProMaxx heads on a smaller 347 stroker, but with 210cc intake ports (that flowed over 320), the heads were better suited to a larger, more powerful stroker combination. Credit for those impressive flow figures goes to full CNC porting, including the 60cc combustion chambers and a 2.08/1.60 stainless-steel valve package. To complete the heads, (they were shipped bare with valves), we installed 939 springs, 4771 spring seats, and 732 titanium retainers, all from COMP Cams.
With the test heads at the ready, we also prepped a set of stock iron, E7TE (5.0L Ford) heads. The heads were upgraded with a spring package to allow for the high-lift, hydraulic roller cam. The stock heads were also run with a set of guided, 1.6-ratio roller rockers in place of the factory units. No changes were made to the ports of the stock heads. Both sets of heads were applied to our stroker test motor, meaning a 351 Windsor-based 393.
The 393 short block featured a forged crank and rods supplied by Speedmaster, along with a set of forged, flat-top pistons from JE. The pistons featured sufficient valve reliefs to allow for our healthy XFI cam profile and a set of Total Seal rings. Since the 393 was sporting extra inches, we chose the larger of the two XFI stroker grinds. The XFI248HR cam offered .608 lift, a 248/258-degree duration split, and 114-degree lsa. COMP also supplied a set of drop-in, hydraulic-roller lifters, hardened pushrods, and a double-roller timing chain. The short block was sealed up using a factory oil pan, Mellings HV oil pump, and ARP oil pump drive. The heads were secured to the 393 short block using Fel Pro 1011-2 head gaskets and ARP head studs. The COMP 1.6-ratio Ultra-Gold roller rockers were covered with a set of Speedmaster cast-aluminum valve covers.
With the long-block portion of our stroker test motor complete, it was time to install our damper, induction, and ignition systems. First up was an internally balanced damper from Speedmaster (with ARP mounting bolt), followed by a single-plane Victor Jr. intake from Edelbrock (sold by Ford Motorsports). Feeding the high-rpm, single-plane was a Holley 950 Ultra XP carburetor. The final touch was an MSD distributor and ignition amplifier.
Run with the ProMaxx heads, the 393 stroker produced 558 hp at 6,400 rpm and 512 lb-ft at 5,000 rpm. Peak power was raised by 171 hp and occurred 1,400 rpm higher, while peak torque jumped by 51 hp and occurred 1,500 rpm higher.
Equipped with Hooker headers, the 393 stroker was run first with the stock iron 5.0L heads. Equipped with the E7TE heads, the 393 produced 387 hp at just 5,000 rpm and 461 lb-ft of torque at 3,500 rpm. We knew the stock heads were restricting the combination, but didn’t know how much until we installed the CNC-ported heads from ProMaxx. After installation, the power output of the 393 soared to 558 hp at 6,400 rpm and 512 lb-ft of torque at 5,000 rpm.
With the right heads, the peak torque occurred where the stock heads made peak power. All told, the head upgrade was worth 171 hp, a clear indication how important it is to choose the right headgear for your stroker.
393 Stroker Head Test-Stock 5.0L vs ProMaxx 210 What looks like the result of adding a supercharger or pair of turbos, is actually from a simple head swap. Replacing the stock E7TE 5.0L Ford heads with the CNC-ported 210s from ProMaxx resulted in huge power gains. Truth be told, the 393 stroker was much better suited to the flow offered by the ProMaxx heads, as the stock versions were designed for a fuel-injected 302 rated at just 225 hp! Test results always look amazing when you replace the one bottleneck in the system, but it does illustrate the importance of planning ahead when choosing performance components for your stroker Ford application.
Sources: COMP Cams, compcams.com; Edelbrock, edelbrock.com; Holley, holley.com; JE Pistons, jepistons.com; Lucas Oil, lucasoil.com; MSD, msdignition.com; ProMaxx Performance, promaxxperformance.com; Speedmaster, speedmaster79.com; Total Seal Rings, totalseal.com
The factory LS roller fulcrum rockers are good, but full rollers are even better.
Words and Photos By Richard Holdener
Why on earth would anyone want to replace the factory rocker arms on an LS application? Aren’t they already roller rockers? Aren’t they already lightweight? Haven’t they been proven effective on countless thousands of high-powered LS applications? The answer to all of these questions is yes, including the first one. Confused? Don’t be, as the factory roller rockers employed on every LS application offer a great many positive qualities, but rest assured, there is additional power to be had with the right rocker upgrade.
As with any modification, replacing the factory rockers with roller rockers might take additional hardware, like pushrods or certainly valve springs, but when you go looking for power, leave no stone unturned. To illustrate the gains offered by upgrading the factory rockers, we ran a back-to-back test using the stock rockers and a set of 1.72-ratio, aluminum roller rockers from COMP Cams. Before getting to the test results, let’s take a look at the test motor.
Rather than run the test one of the many stock LS applications, we decided to compare the rockers on a more dedicated build up. Starting with an aluminum 5.7L block, we proceeded to stroke and poke the LS6 out to 383c.i. The boys at L&R Automotive were responsible for the machining to accept the Speedmaster 4.0-inch stroker crank, JE forged pistons, and K1 connecting rods. Unlike stock pistons, the JE forgings featured valve reliefs to allow use of high-lift (long duration) cam profiles. Minor machining on the bottom of the cylinder bore (for rod bolt clearance) was necessary with this stroker assembly. In addition to the new rings and bearings, Fel Pro also came through with a new oil pump, timing chain, and MLS head gaskets. Use of the 4.00-inch stroker crank meant it was necessary to shim and clearance the factory windage tray using washers and a small mallet.
With a stout short block at the ready, it was time to make some power. First on the To Do list was the proper camshaft. With power and drivability in mind, we selected an off-the-shelf grind from COMP Cams. Though we were running cathedral-port heads, we made our selection from the many rec-port offerings from COMP. The 281LRR HR13 (pt# 54-461-11) featured a healthy .617/.624 lift split, a 231/247-degree duration split, and 113-degree lsa. COMP Cams also supplied a new set of hydraulic roller lifters (pt# 850-16), a set of Magnum pushrods (7.45 inches in length), and the required aluminum roller rockers for the test.
The combination of displacement and our power producers (heads, cam, and intake) combined to
Dialing in the air/fuel and timing curves on the aluminum stroker for our rocker test was this FAST XFI/XIM management system. Consistent air/fuel and timing curves are critical for accurate testing.
produce peak power numbers near 6,500 rpm. The high-lift cam allowed the engine to take full advantage of the flow offered by ported heads, while the duration figures made the sucker rev.
Working with the COMP cam was a set of 243 LS6 cylinder heads. To maximize the flow rate of the factory castings, the heads were shipped off to Total Engine Airflow (TEA) for their Stage 2 porting. The procedure included CNC porting of the intake, exhaust, and combustion chamber, revised valve sizing and a new spring package. The CNC procedure resulted in intake port volumes of 225cc. When combined with the new 2.04-inch stainless steel valves and the CNC chamber work, the results were peak intake flow numbers of 328 cfm at just .600 lift. The exhaust flow was equally impressive through the new 1.57-inch valves, at 270 cfm. More than just peak numbers, the TEA Stage 2 package significantly improved the flow rate of the stock castings through the entire lift range, which is what really makes power.
The final touch on the TEA LS6 heads was a dual valve-spring package combined with titanium retainers. The springs offered enough seat and open pressure, coil-bind, and retainer-to-seal clearance to run cams with as much as .650 lift (perfect for our cam choice). The springs were also sufficient for use with the 1.72-ratio, aluminum roller rockers.
The final power producer employed on the aluminum stroker test motor was a 10-mm, LSXRT composite intake manifold from FAST. To maximize flow to the motor, the intake was teamed with one of FAST’s massive 102mm Big-Mouth throttle bodies. The intake combo was fed by a set of billet fuel rails and 42-pound injectors, all from FAST. Finishing touches on the LS6 stroker included the factory coil packs, a FAST XFI/XIM management system, and a set of 1 7/8-inch stainless steel headers from American Racing (with 18-inch collector extensions).
Prior to start up, the pan was filled with 5W-30 Lucas Oil, and the motor was spun using the starter until oil pressure was visible on the gauge. Once started, the motor was treated to a pair of computer-controlled break-in cycles before running our rocker test. Equipped with the stock rockers, the 383 stroke produced repeatable runs of 578 hp at 6,500 rpm and 542 lb-ft of torque at 4,700 rpm.
After running the stock rockers, it was time to upgrade to the COMP units. For rockers, we chose a set of bolt-down, COMP Ultra-Gold Arc Series rockers (pt# 19024-16). The rockers offered ease of installation (simple bolt-down replacement), a 1.72:1 rocker ratio to slightly increase lift (stock LS was 1.7), and extra strong, CNC-extruded rocker bodies that featured billet trunnions with captured needle bearings. Toss in a roller tip to replace the friction-robbing, factory slider tip and you have the makings of a serous rocker upgrade. The rocker swap was a simple bolt-down affair using the supplied rocker stands to replace the factory unit.
LS Stroker Rocker Test-Stock vs COMP Roller The results of the roller rocker test were interesting, as the roller rockers offered no power gains up to 5,300 rpm. From 5,300 rpm to 6,600 rpm, the gains were substantial, as the change in ratio, reduced friction, and consistent ratio improved the power output by as much as 12 hp. For high-lift cams, the roller rockers will also increase the longevity of valve tips and guides; just make sure you have sufficient valve spring pressure to work with the added weight of the roller rockers.
Once installed, we ran the 383 stroker and were immediately rewarded with additional power. The roller rocker upgrade increased the peak power output to 588 hp at 6,400 rpm, but peak torque checked in at 541 lb-ft at 4,800 rpm. The rockers offered additional power only above 5,300 rpm, with no change in the curve below that porting. It should be pointed out that the extra weight of the rockers will require sufficient spring pressure, but our TEA heads were already equipped for the test. If you are looking for more power, you might try getting off those stock rockers and going roller!
Sources: American Racing Headers, americanracingheaders.com; COMP Cams, compcams.com; FAST, fuelairspark.com; JE Pistons, jepistons.com; K1, k1technologies.com; L&R Automotive, lnrengine.com; Speedmaster, speedmaster79.com; Total Engine Airflow, totalengineairflow.com; Total Seal Rings, totalseal.com
Did we just add a supercharger to a small-block V-8? Look again, that test motor was shy a couple of cylinders!
Words by Richard Holdener
Making power with a big motor is easy; all you have to do is feed the displacement with head flow, cam timing, and a good induction system, and you are set. Making power with less displacement becomes more difficult, but, as this test clearly proves, not impossible.
The key to power extraction for the displacement challenge is obviously boost. There is no better equalizer for cubic inches than a little positive pressure. While adding boost to a stock motor will yield substantial benefits, adding power to a modified one is even better. The extra power offered by the heads, cam, or intake upgrade is actually multiplied by the available boost pressure. To illustrate the torque benefits of boost on a smaller motor, we decided to storm a Chevy 4.3L V-6.
The 4.3L V-6 was Chevrolet’s most successful V-6 platform, and for good reason. Though offering only six cylinders, the 4.3L shared considerable hardware with the small-block V-8. In essence, the 4.3L was a V-8 minus a pair of cylinders (3 and 6). Like the 350 Chevy, the 4.3L combined a 4.0-inch bore with a 3.48-inch stroke. The shared displacement facilitated parts interchange between the V-8 and V-6, including pistons.
Though the V6 utilized the same 5.7-inch rod length, the V-8 and V-6 rods differed in rod journal diameter (due to the 30-degree offset rod journals), and therefore did not interchange. However, the V-6 did share the bore spacing, deck height, and many valve train components with the V-8.
Run in normally aspirated trim, the cammed and carbed V-6 produced 251 hp and 298 lb-ft of torque.
What this meant is that those shared components for the V-6 were readily available at affordable prices. It also meant that the V-6 received many of the upgrades applied to the V-8 over the years, including hydraulic roller cams, one-piece rear main seals, and even the much-praised Vortec cylinder heads.
While running the motor in normally aspirated trim, the factory damper let go in spectacular fashion. To continue testing, we installed a neutral-balance, small-block V-8 damper from Speedmaster.
Knowing the V-6 received the many upgrades, we chose accordingly for our build up. The test motor started out life as a 2002 4.3L from an Astro Van. The 2002 model featured not only the one-piece rear seal, hydraulic-roller valve train, and the high-flow Vortec heads, but also a dedicated balance shaft. Unlike V-8s, the V-6 design was inherently prone to vibration. Use of a balance shaft helped counter some of the unwanted vibration, making these later 4.3Ls much smoother in operation, especially if you plan elevated rpm in a performance application.
Though our V-6 was essentially a rebuild of the long-block components (with .030-over pistons), we did replace some of the factory components before adding boost. Naturally, we ditched the problematic fuel injection for simple and effective carburetion. The EFI intake was replaced by an Edelbrock Performer intake and matching 500 cfm Thunder-Series carburetor. The carbureted induction system required replacement of the computer-controlled distributor with a conventional unit from MSD.
Once the V-6 was topped with carburetion, we took a look inside the motor, more specifically to the cam timing. Naturally, the factory cam timing was purposely mild, and ill-suited to our needs. If you want to find out just how much power our cam was worth, check out the story “The Missing Link” in Power & Performance News. The stock cam was replaced with a COMP 280HR grind that offered .525 lift, 224-degrees of duration (at .050), and a 110-degree lsa. The 280 cam was a solid step up the performance ladder, but could hardly be considered a full (or even 3/4) race grind.
The blower mount featured a dedicated tensioner pulley to tighten the blower belt. Once tightened, we locked it in place using the pulley bolt.
The cam was teamed with a new set of hydraulic roller lifters from COMP Cams. The hydraulic roller valvetrain was one of the many benefits of using this later 4.3L configuration, as it allowed for more aggressive cam profiles (only possible with a roller follower). The 2002 V6 also featured roller-fulcrum rockers (not unlike an LS V-8), but we did upgrade the stock valve springs on the Vortech heads with a set of 26915 beehives, also from COMP Cams.
A set of long-tube headers was the only missing performance ingredient, but run in anger with the stock exhaust manifolds, the carbureted and cammed 4.3L produced 251 hp and 298 lb-ft of torque. Now it was time for boost!
Boost for our V-6 was supplied by a TorqStorm centrifugal supercharger originally designed for a small-block V-8. The 4.3L shared many of the accessories and water pump mounts with the V-8, so the TorqStorm kit bolted right in place. Since the kit’s designed to blow through a carburetor using the supplied carb bonnet, we opted to replace the Edelbrock carb for a Carb Solutions Unlimited unit designed for boost.
The combination of metering block modifications, available jetting and adjustable (boost-referenced) power valves allowed us to dial in the air/fuel mixture under the rising boost curve supplied by the TorqStorm supercharger. The supercharger kit was supplied with an 8-inch crank pulley and 3.25-inch blower pulley.
4.3L V6-Na vs TorqStorm (13.3 psi) Like every other motor in existence, the 4.3L V-6 responded well to boost. Just ask a Typhoon or Syclone owner. Running an Edelbrock intake, Thunder Series carb, and COMP cam, the 4.3L produced 251 hp and 298 lb-ft of torque. After installation of the TorqStorm supercharger and CSU blow-through carburetor, the power output jumped to 460 hp and 423 lb-ft of torque. The peak boost pressure registered during the run was 13.3 psi, which occurred at 5,800 rpm. Both the boost and power curves were still rising at our self-imposed shut off point.
This produced a peak boost reading on our V-6 of 13.3 psi at 5,800 rpm, though there was plenty more boost and power left on the table. We comfortably exceeded 620 hp on a 5.0L V-8 application using this exact blower and pulley configuration, so the sky is the limit if you built a serious V-6 to handle the extra boost. All dialed in, the TorqStorm supercharged V-6 produced 460 hp (459.8 to be exact) at 5,800 rpm and 423 lb-ft of torque.
