The Alter Ego: Twin-Turbo C6 Grand Sport Corvette

The Grand Sport Corvette is an iconic vehicle that dates back to 1962, when Zora Arkus-Duntov was the driving force behind GM’s racing program. The first Grand Sport was designed to take on the Shelby Cobra in the GT Class. After five of these unique track cars were completed, GM found out about the project and pulled the plug. Luckily, the Grand Sport package is still available in the modern Corvettes, adding functional ducts, wider tires, broader fenders, bigger brakes, and Z06 aero. 

While the C6 Grand Sport Corvette was built to be a terror on the road course, our featured ‘Vette takes an entirely different approach. 

Brett Linville is a retired veteran who grew up with a passion for all types of racing. In a small town near Indianapolis, Indiana, Brett often hung around his father’s friend, who owned a C2 Corvette. The C2 struck a chord with Brett, and from that point forward, he knew he would have a Corvette one day. 

After serving our great country in the US Army for most of his life, the time came for him to retire. At the end of 2010, Brett fulfilled his childhood dream as he bought a beautiful 2011 Cyber Grey Grand Sport C6 straight off the showroom floor. Within a few weeks, he had a full exhaust on the car, and shortly after that, added a supercharger. Brett claims he never planned to go full tilt with it, but of course, we all know how that goes.

After a few years of toying with the supercharged setup, Brett began wanting more. 

In 2015, he decided to go all-in and take his C6 to the next level. The stock LS3 was removed and a stroker motor was put in its place. The guys at TKM Performance in Denton, North Carolina handled assembly for the new mill. They started with an ERL Performance Superdeck iron-sleeved aluminum block. They then bored it to accept the 4.175-inch Diamond Racing 11:1 pistons that are connected to a 4-inch stroke Callies Dragonslayer crank with ultra I-beam connecting rods. The 438 cubic-inch engine was then stuffed with a stage three hydraulic roller Brian Tooley Racing turbo cam to complete the short block.

For the top end of the engine, a set of Trick Flow LS7 aluminum heads were used along with 2.200-inch intake valves and 1.600-inch exhaust valves and LS7 rockers. The long block was then finished up with an LS7 intake manifold and a Holley Performance 92mm throttle body to satisfy the engine’s air needs. For fuel, multiple Holley fuel pumps were used in conjunction with a Holley regulator to feed the Bosch 2100cc injectors.

Mayhem Motorsports handled the custom twin-turbo kit from beginning to end. The system is based on two Forced Inductions billet S369 turbos with a custom 2.5-inch hot side, 3-inch cold side, and 3-inch downpipes. They also fabricated an intercooler in-house for this project. Expelling the spent exhaust gases and excess boost pressure are JGS Precision wastegates and blow-off valves. This trick setup allowed them to place the downpipes and wastegate dumps directly behind the turbos and out the front fenders. This configuration helps with backpressure and looks menacing to boot.

 

At this point, the factory ECM wasn’t cutting it and was removed in favor of a Holley EFI system. Jeff Rhodes worked his magic on the tuning as the C6 hit the dyno rollers at Mayhem Motorsports. Being that this 438 cubic-inch stroker has quite a bit more cubes than your typical small-block, along with two hairdryers, on just 17-pounds of boost the team was able to muster 1,224 horsepower and 1,282 lb-ft of torque at the wheels while using Red Ignite E90. 

Brett knew that he needed a sturdy drivetrain to hold up to the torque that the motor was capable of producing. Since he wanted to compete in stick-shift racing, he needed the best parts on the market to hold up to the twin-turbo torque monster. An RPM Transmissions-built TR6060 with a McLeod RXT HD clutch, and an MGW shifter was called upon for this task. From there, the stock rearend housing wouldn’t handle the power, so RPM beefed-up the housing and stuffed the unit with 3.42 gears and Driveshaft Shop axles were installed to make sure the power made it to the tires.

Tires and wheels are always a key talking point when it comes to performance and style, and there’s just something about a C6 Corvette on a set of bigs and littles that commands attention. Up front sits a set of Weld Racing Alumastars wrapped in Mickey Thompson (M/T) 26-inch front runners. On the rear, you can find a set of MacFab bead-locked 15-inch Weld S71s with some M/T 28-inch slicks mounted on them. To get the 15-inch rears on the Corvette, Carlyle Racing sent over a rear brake conversion so the smaller diameter wheels would bolt-on effortlessly. Strange Engineering drag brakes were utilized on the front, which helps save some weight over the stock Grand Sports big brake kit. Aside from a set of Menscer Motorsports front and rear coilovers shocks, the factory suspension stayed intact.

You would be hard-pressed to argue that this C6 Grand Sport doesn’t have some killer lines. With the addition of a Z06 wing, beauty rings around both wastegate dumps along with the downpipes, and a wicked stance, you know this car is serious business even if you didn’t see the parachute at first glance. 

When you’re inside the cockpit, the first thing you notice is how much of the factory interior was retained. The dash, carpet, and door panels remain, and the only thing that was touched were the seats. A set of Kirkey’s Racing seats were installed to save some weight. Mayhem also built a roll cage that was even paint-matched to match the car’s exterior. A Stroud fire suppression system was also mounted inside for extra safety.

By now, you’re probably wondering how fast this street-legal six-speed Grand Sport is in the 1/4-mile — the best pass on the 1320 is a 9.05 at 161 mph, with a 1.32 short time. However, Brett doesn’t just drag race the car, he’s competed in multiple 1/2-mile events where he has been a best of 184 mph. Brett wanted a car he could do both types of racing with while being able to drive on the street. Most would agree he was successful in his endeavors, as he can be found competing in Street Car Takeover events on the East coast as well as stick shift and 1/2-mile races. 

Brett would like to thank the ARMY for giving him a career that he was able to retire from and enjoy his favorite hobby, as well as his friends over at Mayhem Motorsports and The Nano Pros, that are just a phone call away when he needs something.  

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