Here’s C6.R No. 4 in Corvette...
Here’s C6.R No. 4 in Corvette Racing’s paddock at Sebring on February 23, 2011. The car had just passed tech inspection for the annual 12 Hours of Sebring enduro.
Corvette Racing's C5-R and C6.R Corvettes are among the most recognized road-race cars in the world, and for good reason. In the 12 years since the first iterations of these factory racers were introduced at the 24 Hours of Daytona on February 5, 1999, the Vettes officially known as No. 3 and No. 4 have won 79 races (through 2010), including eight American Le Mans Series (ALMS) Manufacturers' Championships, seven ALMS GT1 Drivers' Championships, seven Sebring 12-hour and eight Petit Le Mans class wins, and six class wins at the 24 Hours of Le Mans.
In "C6.R Up Close and Personal," (VETTE, September '07), we spotlighted many of the features that differentiated these cars from a production Z06, and got to know some of the crewmembers who kept them in race-winning condition.
Corvette Racing introduced the second- generation C6.R to compete in the production-based GT2 category (since renamed GT) in August 2009. The cars were homologated on the Corvette ZR1, and shared the supercar's body design, aerodynamic package, aluminum frame and chassis structure, steering system, windshield, and other components.
In the months leading up to the 2011 season, Corvette Racing stayed busy around the clock, designing and building two all-new C6.Rs to meet the latest GT-class regulations established by the Le Mans and ALMS races' governing body, the Automobile Club de l'Ouest (ACO).
Given all the engineering, technological, aerodynamic, and cosmetic changes that have been made to the C6.Rs since our last story ran four years ago, we thought it would be apropos to ask Chevrolet for a private look at the latest version. Our guide was Corvette Racing Program Manager Doug Fehan, who gave us a close-up look at the No. 04 car and explained how this most recent edition differs from its predecessors.
Special thanks to Corvette Racing Trackside Press Relations Manager Rick Voegelin and Doug Fehan for making this story possible.
The Corvette C6.Rs are powered...
The Corvette C6.Rs are powered by 5.5-liter, naturally aspirated GM small-block V-8 engines. They’re based on the 7.0-liter LS7 powerplant and use production aluminum blocks along with heavy-duty cylinder heads. The engines feature a smaller cylinder-bore diameter (4.090-inch) and a shorter stroke (3.185 inch) than the production LS7 to reduce displacement to meet GT-class rules. The series also “equalizes” the performance of engines of various types and sizes by requiring intake-air restrictors. Thus the Corvettes’ engines breathe through a pair of 28.8mm restrictors that are located in front of the sealed airbox, which limit engine output to 485 horsepower at 5,800 rpm.
The Corvette race cars are...
The Corvette race cars are using purpose-built Bosch 5-series motorsports engine-management systems in 2011. “Corvette Racing engineers worked very hard on the communication system that links the new engine-management system and the paddle-shift system,” says Fehan. “We’ve also adopted a new power control system that automatically performs many of the functions that used to be done manually, such as turning on the reserve fuel pump and switching the batteries during pit stops.”
The Xtrac sequential six-speed...
The Xtrac sequential six-speed transaxle has interchangeable gear ratios that can be tailored to different tracks. The gearbox is equipped with a pneumatic Megaline two-way shift cylinder that works in conjunction with the paddles on the steering wheel and an electronic control system to change gears. The shift cylinder replaces the conventional gearshift lever.
To stay below the maximum...
To stay below the maximum noise levels specified in the ACO rulebook, mufflers are located inside the race cars’ rocker panels. The exhausts exit below both doors, where shields protect the composite body panels from exhaust heat.
GT rules require the use of...
GT rules require the use of ferrous (steel) brake discs, rather than the exotic (and expensive) carbon-carbon rotors that the C6.R cars used in the GT1 class. The brake pads’ composition is changed according to the race distance—more aggressive pads are used for sprint races, while harder, longer-lasting pads are fitted for endurance events.
The GT regs also mandate a...
The GT regs also mandate a 1-inch wicker, or “Gurney flap,” at the rear of the Corvette C6.R’s carbon-fiber wing. In previous years, this piece’s height could be changed to increase or decrease downforce and the resulting drag.