Forced induction and the Corvette-seemingly a match made in heaven. When Chevrolet introduced the LS1 between the fenders of the new C5 in 1997, members of the automotive aftermarket and enthusiast community could not have imagined the performance revolution the engine would soon spark. As the LS powerplant family and related parts grew, so did the public's desire for increased horsepower and torque. Fortunately for them, the engine's deep-skirt design and 6-bolt main caps offered almost unlimited potential for innovative builders to create stratospheric power levels.
Two such forces in the industry are Motorsport Technologies and Squires Turbo Systems (STS). Long regarded as one of the Corvette world's top tuners, Motorsport Tech has fielded a plethora of nasty Vette rockets that have competed in everything from the One Lap of America to the back alleys of suburban America. It's not surprising, then, that when STS stormed into the C5 market with its rear-mounted twin-turbo setup, Motorsport Tech was right there to push the kit to the next level.
A case in point is the dazzling silver Z06 of Garett Oliphant, a self-employed entrepreneur who founded the Web-based Houston Performance Driving Club. "After owning two slightly modified C5s over the last five years, I bought a pristine, 9,000-mile '03 Z06 from a fellow member of the club," says Oliphant. "After modifying the stock LS6 with an insane cam and a direct-port nitrous system, the car put out over 500 rear-wheel horsepower."
Most Corvette enthusiasts would have been happy with such impressive output, but Oliphant had something considerably more ambitious in mind. Specifically, he wanted to build one of the fastest street-legal Vettes in the nation. "Forced induction was a given," he says, "but to reach my goal of over 1,000 rear-wheel horsepower, an off-the-shelf system wasn't going to cut it. Jayson Cohen of Motorsport Tech and Rick Squires of STS worked with my head porter and camshaft designer to create a big-cube mill that would be an absolute beast on the street."
Motorsport Tech started with a fresh GM Performance Parts 6.0-liter LQ4/LQ9 block as the basis for the engine build. Thanks in part to the rigidity of the iron block, the company was able to punch the stock 4.00-inch bore out to 4.030 inches and enlarge the factory 3.622-inch stroke to 4.00 inches with a Lunati 4340 forged crankshaft. Lunati Pro-billet steel I-beam connecting rods measuring 6.125 inches push the displacement to 408 cubes.
In order to evacuate the cylinders in a rapid fashion, the stock LS6 heads underwent Stage III head porting by Greg Good. After enlarging the combustion chambers and performing extensive porting, Good outfitted them with Ferrea stainless intake and exhaust valves measuring 2.08 and 1.60 inches, respectively. All that work paid off with flow ratings of over 355 and 250 cfm (at 0.600) on the intake and exhaust sides. Compression checks in at a boost-friendly 9.5:1.
Comp double springs and hardened chrome-moly pushrods work in conjunction with a fresh set of Crane hydraulic roller lifters and Jesel shaft-mounted roller rockers to keep the valvetrain stable under boost. Intake duties are handled by an Edelbrock Victor Jr. intake fitted with a Motorsport Tech custom intake elbow and a 90mm LS2 throttle body.
Exhaust is routed to the twin 60-1 Limit Engineering ball-bearing turbos via a set of Kooks 171/48-inch stainless headers and a Kooks off-road mid-pipe with integral X. Thermo-Tec header wrap was liberally applied from the headers all the way back. Dual TiAL 38mm wastegates, a 29-inch-core STS intercooler, and an Alkycontrol methanol-injection kit enable 13.5 pounds of boost on 93-octane pump gas. In order to keep the oil flowing through the expensive ball-bearing turbos, a second STS oil pump was added to the rear of the Z06.
To bump output above the 1,000 rwhp mark, a Nitrous Express nitrous system was plumbed into the junction just before the throttle body. Set up to deliver a 150-horse shot, the system provides an extra measure of cylinder pressure and intercooling, allowing the engine to consistently run intake air temperatures of less than 100 degrees, even after hot-lapping.
Rather than converting the Z06 to an automatic transmission to handle the brutal power, Garett contacted Liberty High Performance, of Taylor, Michigan, and had the company rebuild his T56 with its heavy-duty Pro-Shift gear modifications. Power is applied through a SPEC Stage V clutch and aluminum flywheel to a stock-geared rear differential.
A Dynotech hardened output shaft and cradle brace keep the rear IRS in one piece, while stock sway bars and polyurethane bushings work in concert with new suspension bolts and cut bushings to drop the car two inches closer to the pavement and allow razor-sharp maneuverability.
Hennessey Venon R5-S wheels shod with super-sticky BFG g-Force KDW (front) and Nitto Extreme Drag (rear) tires provide a footprint sufficiently massive to keep the car planted to the pavement. Baer Eradispeed rotors and Carbotech Panther XP pads provide enhanced stopping ability, while a set of Corbeau A4 seats and harnesses keep the owner firmly ensconced in this boosted rocket.
Realizing that street credibility is earned and not given, Oliphant decided next to upgrade the boosted Z06's look to match its prodigious output. Richey Collision in Houston began by adding a Lingenfelter/Starcraft high-rise hood, after which he applied subtle ghost flames to the front fenders and doors of the Quicksilver Metallic Z. Rounding out the exterior is a custom-painted, Spiral Gray rear valance panel that helps integrate the black wheels and fender extractors.
For now, anyway, Oliphant seems satisfied with the outcome of his project. "Driving the car on the weekends and on nice days is intoxicating," he says. "Although the camshaft features a long-duration cam, the car still drives around in a very civilized manner. Where the car really shines, though, is on the streets, after hours, against some of the fastest street cars in the area. When the ravenous 408 gets into boost, and I am able to step into the nitrous for some additional power, all the competition sees is a silver ghost evaporating into the ether."