Whether it be in corporate America, sitting behind a government-issue desk in the Pentagon, or on Madison Avenue with feet propped up on the finest imported cherry, Americans love to dream and compete-not necessarily in that order. Who among us hasn't watched an NFL game and dreamed of running a skinny post, catching the game-winning touchdown pass, and soaking in the cheers of thousands of fans?
Although catching a touchdown pass is farfetched for some, it sure isn't for Dez White, a pro football player most recently with the Atlanta Falcons. According to Dez, "Being a pro athlete is a brutal job that is both exhilarating and dangerous. Nothing beats the thrill of catching a touchdown pass, and the resulting adrenaline rush. Conversely, catching a 7-yard crossing pattern and getting drilled by an opposing linebacker or safety may make it difficult to even get off the training table for days on end."
In order to provide an off-the-field adrenaline rush, Dez purchased a used '01 Vette. Other than a Corsa converter-back exhaust, the 12,800-mile one-owner car was bone stock and in show-ready condition. Having loved cars all of his life, Dez found the Vette to be a dream come true. It was also the perfect canvas for creating a fun car that would be equally at home running laps at Road Atlanta or going to a local car show.
After attending a private track event at Road Atlanta with some of his buddies from the Falcons, Dez realized just how much he enjoyed pushing the C5 to its limits on a road course. On the downside, it became evident that the stock C5 couldn't compete against the exotic Porsche 911 Turbos and Italian sports cars his teammates piloted. "Since the sight of receding taillights was unsettling, I began researching the market for powerplant and handling upgrades that would allow me to reverse the tables and show the competition how America's favorite sports car dismisses the highbrow Europeans," Dez tells us.
After surveying the market, Dez turned to Motorsport Technologies Inc. (MTI), in Houston, Texas, to transform his '01 C5 into an MTI Z07 twin-turbo. With 12 years' GM-tuning experience and an impressive resume that includes building the '02 Z06 Corvette that won the '03 One Lap of America race, MTI was tasked with engineering a combination that would meet the owner's horsepower goals, while still retaining the driveability characteristics necessary to take in a cruise or car show on a moment's notice. According to Jayson Cohen, owner of MTI, "With a goal of 850 crankshaft horsepower and excellent driveability, a C5-R-based 427 featuring either one or more turbochargers or a supercharger would have to be employed to achieve optimum power and reliability. With over five years' experience building C5-R-based 427s in-house, we simply had to determine what configuration of power adder to use to meet the goals. Since the LS1-based STS [Squires Turbo Systems] twin-turbo systems were performing excellently on several customers' C5s, we consulted with [STS founder] Rick Squires to discuss customizing one of these C5 twin-turbo kits for the application."
By upgrading the turbos from T3/T04B units with 48mm compressors to Limit Engineering 60-1 compressors and high-flow turbines capable of well over 1,000 hp, Cohen and Squires were able to increase the top-end capabilities of the system and meet the power goals. By utilizing MTI's mild "G1" camshaft, the excellent low-end torque of the 427 was retained, while still providing a brutal top-end punch once the engine builds boost.
The transition from relatively mild 427 to steroidally enhanced monster kicks in just below 3,500 rpm, and the power doesn't crest until 6,100 rpm, where 785 rear-wheel horsepower register. With the GReddy boost controller set to kill on 12.5 psi of boost, the engine tops the 600-rwhp mark at only 4,500 rpm and pulls over 700 rwhp all the way to the redline of 6,600 rpm. Even on its conservative low-boost (8 psi) setting, the Vette pumps out in excess of 600 rwhp.
In order to achieve those lofty numbers, MTI started with a fresh GM Performance Parts C5-R block and utilized the intended 4.125-inch bore and 4.00-inch stroke to arrive at 427 cubic inches. To achieve a boost-friendly compression ratio of 9.0:1, a set of GM's truck-based LQ9 heads and custom Wiseco forged pistons were bolted on. MTI's Stage III porting and larger Ferrea stainless valves allow the heads to flow over 330 cfm at 0.600-inch lift on the intake side. Ferrea double springs and a set of Jesel shaft-mounted rockers keep the valvetrain stable and capable of exacting valve events. Intake duties are handled by a FAST composite intake paired with an LS2 90mm throttle body. To keep the fluids from boiling during high-rpm blasts, a Ron Davis aluminum racing radiator with built-in oil cooler was also installed.
One of the most challenging aspects of the build was supplying enough fuel for the boosted 427. A set of Walbro-based 255-lph in-tank pumps feed AN-10 braided lines, Aeromotive high-flow fuel rails, and Mototron 60-lb/hr injectors. Also integral to the safety of the engine is an MTI custom tune created with LS1Edit. A total of six hours of combined dyno-testing and road work were required to satisfy both low- and high-boost conditions.