Starting Point: A Salvage-Yard Gen VI 454

A trip to the local Pick Your Part yard turned up what we were after: a Gen VI 454 (7.4L), produced by GM from 1996 through early 2000. The Gen VI is a strong candidate for forced induction. Factory-equipped with small-chamber, standard-size oval-port heads, a hydraulic roller cam, and 9.0:1 static compression, it also carries a four-bolt main block and steel crank. Offered originally with a long-runner EFI induction system, the 454 converted to carbureted trim using a Speedmaster Eliminator intake, Holley carburetor, and MSD distributor. After inspection, the engine delivered a solid oil-pressure curve and baseline numbers of 370 hp and 476 lb-ft of torque - consistent with what we have measured across five of these junkyard 454s with this induction setup.

Test 1: Zex Perimeter Plate Nitrous - 125 hp Shot

The first power-adder was a Zex Perimeter Plate nitrous system. The Perimeter Plate uses 12 equally spaced injection points to ensure even distribution to all cylinders. Jetting was set for a 125 hp addition on pump gas - appropriate for a stock bottom-end 454.

With the bottle heated to proper pressure, the Zex system delivered peak numbers of 530 hp and 662 lb-ft of torque. The power curves confirmed a consistent 125 hp gain through the tested rev range.

Test 2: Comp XR276HR Cam Swap

The factory truck cam was replaced with a Comp Xtreme Energy XR276HR, chosen for its balance of performance gain and retained drivability. The XR276HR offers 0.510-inch lift, a 224/230-degree duration split, and 110-degree LSA. A set of Comp beehive valvesprings (PN 26120) accompanied the swap.

Results: peak power climbed from 370 hp and 476 lb-ft to 428 hp and 515 lb-ft. The cam delivered over 60 hp at 5,000 rpm and improved output even at 2,600 rpm. Equally important, the cam upgrade set a stronger foundation for the boost tests to follow.

Test 3: Vortech YSi Supercharger - 19 psi

With the cam in place, the engine moved to forced induction. Vortech supplied a YSi supercharger kit rated for over 1,200 hp, driven by a cog pulley system to eliminate belt slippage. The standard Holley carburetor was replaced with a dedicated blow-through unit and bonnet from CSU (Carburetor Solutions Unlimited). Race fuel was used to eliminate detonation risk at elevated boost.

At 19 psi of non-intercooled boost, the supercharged 454 produced 791 hp at 6,000 rpm and 713 lb-ft of torque at 5,300 rpm. An intercooler would push those numbers further.

Test 4: Twin-Turbo BorgWarner Setup - 12.3 psi

The final configuration used a pair of BorgWarner turbos supplied by Lil John's Motorsports Solutions (LJMS), fed through custom stainless turbo headers from JFab and an air-to-water intercooler from CXRacing. Boost was controlled by a pair of TurboSmart Hyper-Gate45 wastegates. The CSU blow-through carburetor and bonnet carried over from the supercharger test. Race fuel was used again.

Boost was increased incrementally to a maximum of 12.3 psi. The twin-turbo Gen VI produced 832 hp and 866 lb-ft of torque. Each BorgWarner turbo was capable of supporting this power level individually; running a pair reduced backpressure and maximized output.

Build Details

The factory EFI induction was replaced with a dual-plane Eliminator intake from Speedmaster.

Baseline testing used a Holley 650 XP carburetor, sized appropriately for the mild 454's output.

An MSD billet distributor replaced the factory EFI unit.

Fresh from the yard, the carbureted 454 produced 370 hp at 4,600 rpm and 476 lb-ft of torque at 3,400 rpm.

The Zex Perimeter Plate featured 12 equally spaced injection ports for consistent cylinder-to-cylinder distribution.

Adjustable jetting allowed precise power-level selection. The 125 hp jets matched the stock 454's bottom-end limits.

With the Zex system active, the Gen VI 454 reached 530 hp and 662 lb-ft. The graph confirms a minimum 125 hp gain across the tested rev range.

The Comp XR276HR cam offered 0.510-inch lift, a 224/230-degree duration split, and 110-degree LSA - enough to improve output without sacrificing street manners.

The stock spring package was replaced with beehive springs, retainers, locators, and keepers. The cam swap delivered gains from 370 hp and 476 lb-ft to 428 hp and 515 lb-ft - over 60 hp at 5,000 rpm.

The Vortech YSi supercharger kit supports over 1,200 hp and uses a cog drive system to prevent belt slippage.

CSU supplied a blow-through carburetor built specifically for boosted applications.

CSU also provided a blow-through bonnet for their modified 850 Holley carburetor.

At 19 psi through the cog drive system, the supercharged 454 produced 791 hp and 713 lb-ft. Intercooling would extend these numbers further.

The twin-turbo configuration used a pair of BorgWarner units, each rated for over 900 hp. Running both reduced backpressure and maximized efficiency.

Custom stainless turbo headers fabricated by JFab fed the BorgWarner turbos.

A pair of TurboSmart Hyper-Gate45 wastegates managed boost pressure.

An air-to-water intercooler from CXRacing cooled the charge. Dyno water was used during testing; ice water would yield additional power.

At 12.3 psi of boost, the twin-turbo 454 produced 832 hp at 5,500 rpm and 866 lb-ft of torque at 4,400 rpm.

Results Summary

Starting from a 370 hp baseline, four power-adders were tested on a single junkyard Gen VI 454. Nitrous added a consistent 125 hp. A cam swap brought the naturally aspirated output to 428 hp and set up the engine for boost. The Vortech supercharger reached 791 hp at 19 psi without intercooling. The twin-turbo configuration topped out at 832 hp and 866 lb-ft at just 12.3 psi with intercooling. The stock short block and heads handled all four configurations without issue - a direct testament to the Gen VI's engineering margin.