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2011 Corvette Racing C6.R - Portrait Of A Performer
An inside look at the 2011 Corvette Racing C6.R
Christopher R. Phillip
Aug 1, 2011
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2011 Corvette Racing C6.R - Portrait Of A Performer
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.
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 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 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 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 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 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.
The GT1 version of the Corvette C6.R featured sectioned and widened front fenders with aerodynamic louvers on the top surface. GT rules require that the bodywork match the production ZR1 fender, with only flares used to cover the wide racing rubber.
Previous incarnations of the Corvette C6.R racers, including last season’s cars, featured a flush rear valance. One of the aerodynamic refinements made to the 2011 versions is this cutout between the diffuser and the trailing edge of the rear wheelwell.
GT rules require teams to use one rear-wing design throughout the season, and the rulebook stipulates this unit’s maximum width and length. After the wing is submitted by a team and approved (homologated) by the ACO, it can’t be changed. Consequently, the Corvette Racing engineers designed a hybrid wing that would perform on high-speed, low-drag tracks like Le Mans and Road America, as well as on high-downforce circuits like Long Beach and Lime Rock. The mounting brackets allow the wing’s angle to be adjusted in small increments to fine-tune the downforce.
Michelin works closely with Corvette Racing, providing the team with tires in multiple compounds to suit a variety of track and weather conditions. During an endurance event like the Sebring 12-hour or the 24 Hours of Le Mans, different tire compounds may be employed throughout the race, depending on the temperature of the racing surface. The tires are mounted on new-design BBS aluminum wheels, sized 18x12.5 inches (front) and 18x13 inches (rear).
Of these three flush-mounted lights integrated into the outer door skins, can you guess which one is most important to Corvette Racing? If you answered, “The top one!” you’re correct, since the lights display the C6.R’s position during the races. From top to bottom are First, Second, and Third Place. They’re controlled remotely by the series’ timing and scoring systems.
A pair of hydraulic connectors on the right-side roof support allow the crew to add oil to the engine and gearbox from pressurized canisters during pit stops. The stabilizer-bar stiffness can be adjusted with a wrench.
The C6.Rs are equipped with onboard pneumatic jacks, which raise and lower the cars for tire changes. During pit stops, a mechanic plugs in the high-pressure (300 psi) hose and opens a valve to raise the car; when he disconnects the hose, the car drops safely and the driver starts the engine.
This crush structure, positioned starboard of the driver-side door, is made of honeycomb aluminum with a high-strength Kevlar skin. Developed by GM Racing and first used in the Corvette C5-R, this structure absorbs energy in the event of a side impact, protecting the driver by deforming under load to cushion the blow.
Many of the C6.R’s cabin controls and switches—including the car-to-pit radio, windshield wipers, lights, traction control, engine map, air conditioning, reserve fuel pump, and engine start—have been relocated from the dashboard to the steering wheel for 2011. “The steering-wheel system is more user friendly, and drivers of various sizes can reach the switches more easily,” says Fehan.
The ACO now allows paddle-shift transmissions in the GT category, and Corvette Racing has adopted this technology to the C6.Rs. The paddles are functionally similar to the ones found in production Corvettes, and allow drivers to change gears with both hands firmly on the steering wheel. Unlike the factory setup, the C6.R system uses the righthand paddle for upshifts, and the lefthand paddle for downshifts. “The paddle shift is a big plus, particularly in the braking zones,” says C6.R full-time driver Oliver Gavin. “You can get hard on the brakes, then downshift really quickly. Going up through the gears, the shifts are smooth and solid. In terms of consistency and reliability, the system is a really good step forward. I will confess that during the first test, I kept reaching for the stick, which wasn’t there!”
GM Racing pioneered the use of right-side driver-safety nets in the mid-’90s, and this feature is now used in many forms of motorsports. The net prevents sideways motion of the driver’s head during an impact. The onboard camera gives TV viewers a look at the driver at work during ALMS broadcasts.
The Corvette race cars were equipped with air conditioning before these systems were made mandatory. The current version uses a compressor from GM’s electric-car program, and the team has refined the condenser and evaporator to maximize cooling efficiency using production GM components. Cool air is circulated through the cockpit and pumped through holes in the driver seat. The driver also breathes cool air through a hose connected to his helmet (not shown).
Wireless telemetry transmits data from the Corvettes to the engineers in the pits, who monitor operating parameters such as tire pressure, fuel consumption, coolant temperature, and oil pressure in real-time. Since the volume of data collected is so large that only a portion of it can be sent via the airwaves, a high-speed connection is plugged into the C6.Rs during pit stops for a full download. The readings are then routed to a network system on the pit stand and analyzed by the team’s engineers.
Chevrolet was established in November 1911 by racer Louis Chevrolet and General Motors founder William C. “Billy” Durant, and its cars quickly earned a reputation for performance, durability, and value. Corvette Racing is saluting Chevy’s 100th anniversary in 2011 with these special centennial graphics created by GM Design. They are affixed to the C6.Rs’ front fenders.
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