The $500 Question: Budget Boosted Big Block

Everyone loves to make big power but, as the old saying goes, speed costs, how much do you want to spend? This is especially true of big blocks, as costs seem to increase in proportion to displacement. What if we told you there was a place where displacement was irrelevant and a complete big-block 454 could be had for a little as $500? Now what if we told you it was possible to easily coax over 800 horsepower from this same $500 454 with minor mods and a little boost, would you be interested?

Obviously the answer is yes, as who in their right mind wouldn’t jump at the chance to score a big-block Chevy for just $500? The answer to the $500 question is as close as your local wrecking yard, where we walked home with a complete, running 454 from a 1-ton truck for just five bills. Not long ago, this 7.4L was priced the same as every other V8 in the yard, regardless of displacement, but someone recognized that people will pay more for the 7.4L big block than a comparable 5.7L mouse motor. Even with the recent price increase, 500 bucks for a complete, running 454 is still a pretty sweet deal.

As good as the $500 454 is, the stock L29 truck motor (circa 1999) was originally rated at 290 hp and 410 lb-ft of torque. In addition to the displacement, the 454 offered a number of desirable features that made it ideal for future forced induction. Unlike the previous Gen V motors that relied on peanut-port heads, the Gen VI L29 featured large, oval-port heads to increase flow. The 4-bolt main L29 also featured a boost-friendly 9.0:1 compression.

Originally port fuel injected (Gen Vs featured throttle body injection), we replaced the Gen VI injection with a more conventional (and inexpensive) carbureted induction system that included the tried-and-true Edelbrock Performer RPM Air Gap intake and 750 Holley carburetor. The final two mods performed to the junkyard 454 included a mild cam and Fel Pro MLS head gaskets. Having logged 150,000+ miles, we had no idea what condition the stock head gaskets (or any of the internals for that matter) were in, so we opted to yank the heads and sneak a peak. Everything was in perfect running condition, so we installed new head gaskets using the factory head bolts (ARPs would be a better idea here).

With a decent induction system, head flow and displacement, the factory cam seemed to be the limiting factor in terms of power output on the L29. Despite having low compression and valve reliefs in the stock flat-top pistons, available piston-to-valve clearance ultimately limited our cam choices. We stepped up as far as we could (leaving a tight .065 intake P-V clearance) with an XM284HR cam from COMP Cams. The XM cam featured .547 lift on both the intake and exhaust combined with a 230/236-degree duration split and 112-degree lsa.

The 1999 L29 was factory equipped with a hydraulic roller cam so it is possible to reuse the factory hydraulic roller lifters (we installed COMPs). The high-lift cam and attending increase in engine speed necessitated a valve-spring upgrade. The well-worn stock springs were replaced by a set of 26120 beehive springs (and attending hardware) from COMP Cams. These springs allowed the 454 to buzz safely to 6,000 rpm or well above the power peak. The new cam and springs were used with the factory Gen VI (bolt-down) rockers, guide plates and 5/16ths pushrods. Our only issue with the 454 was a slipping balancer that provided inaccurate timing values, which we cured by remarking the inner hub after positioning number 1 cylinder at TDC.

No matter how well they worked, adding a cam and intake manifold to the stock 454 was only going to get us half way to our goal of 800 horsepower, so we needed a multiplier. Enter the twin turbo set up. The twin system revolved around a pair of Borg Warner 475s supplied by Lil John’s Motorsport Solutions. Originally sourced for a more powerful 6.0L LS project, they were right at home on this mild 454. Given that each Borg 475 was capable of supporting 1,000 horsepower, they were more than a tad overkill on this application, but the results speak for themselves.

The 90-degree adapters featured standoffs for a pair of Hyper-gate 45s from Turbo Smart. The wastegates were configured with 9-psi springs.

The 90-degree adapters featured standoffs for a pair of Hyper-gate 45s from Turbo Smart. The wastegates were configured with 9-psi springs.

The turbos were teamed with a set of custom turbo manifolds from Jason Trejo at JTFAB. The manifolds featured heavy-wall tubing, thick head flanges and V-band clamps to ensure leak-free sealing. The turbo manifolds fed a pair of 90-degree adapters designed to mount the T4 475 turbos. Each adapter also featured a provision for a 45mm Hyper-Gate wastegate from Turbo Smart. Boost was fed through a dual-core, air-to-water intercooler from CX Racing to a 90-degree carb bonnet and blow-through carburetor from Carb Solutions Unlimited. The discharge tube connecting the exit of the intercooler to the 90-degree carb bonnet also featured a Turbo Smart Race Port blow-off valve.

The first order of business was to run the motor normally aspirated. Equipped with the COMP XM cam, Edelbrock intake and 750 Holley carb, the mild L29 454 produced 428 hp at 5,400 rpm while grunting out 504 lb-ft of torque at 3,800 rpm. Adding boost from the custom twin-turbo system resulted in some serious power. Running 9.3 psi (9-pound wastegate springs) resulted in peak numbers of 733 hp and 764 lb-ft of torque. The combination of low static compression, intercooling and the additional charge cooling from the carburetor allowed us to safely run this boost level on pump gas.

Using Westech’s TC-1 Turbo (boost) Controller from Daytona Sensors, we adjusted the boosted pressure up in small increments to 11.0 psi where the 454 thumped out 786 hp and 821 lb-ft of torque. The final adjustment to the wastegate controller brought boost to 12.3 psi, where the turbo L29 thundered out 832 hp and 866 lb-ft of torque. That, my friends, is some serious power for a budget boosted big block, and the best part, there is probably even more waiting to be unleashed, but the answer to that question will cost more than $500.

Fresh from the wrecking yard, the L29 454 was upgraded with a new, carbureted induction system and mild Comp cam. Run in normally aspirated trim, the carbureted 454 produced 428 hp and 504 lb-ft of torque. Adding a pair of Borg 475 turbos to the mix plus an air-to-water intercooler upped the power ante considerably. Running just 9.3 psi of boost, the boosted BBC thumped out 733 hp and 764 lb-ft of torque.

Thanks to the Daytona Sensors TC-1 boost controller, increasing the boost and power output required just a few turns of the control knob. Increasing the duty cycle of the controller allowed us to increase the boost pressure supplied to the L29. The combination of a low static compression, ATW intercooler and further charge cooling from the carburetor allowed us to safely crank up the boost. Stepping up from 9.3 psi to 11.0 psi resulted in a jump from 733 hp and 764 lb-ft of torque to 789 hp and 821 lb-ft. The final jump to 12.3 psi resulted in 832 hp and 866 lb-ft of torque or enough to put a Camaro or Chevelle comfortably into the 9s.

Sources

COMP Cams
compcams.com

CSU
csucarbs.com

CXRacing
cxracing.com

Daytona Sensors
daytona-sensors.com

DNA Motoring
dnamotoring.com

Edelbrock
edelbrock.com

Holley/Hooker/Weiand
holley.com

JTFAB
(909)525-8220

Lil John’s Motorsport Solutions
liljohnsmotorsports.com

About the author

PPN Editor

Power & Performance News is the source for news, tech and products that help you get more performance from your vehicle. If powertrain performance projects and hardcore technical content are your interest, Power & Performance News is the publication designed for you. Our acclaimed editorial staff covers all aspects of engine and driveline upgrades with a mission of presenting information that is both interesting and achievable for the “average car guy”.
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