Over the past 10 years, Corvette Racing has become a dominant force in international sports-car racing, to the extent that for the past two seasons, the C6.Rs have run essentially uncontested in ALMS GT1. The GT2 class, meanwhile, has developed a healthy field of factory-supported competitors representing BMW, Ferrari, Porsche, Panoz, and Jaguar. (Audi is currently mulling its own GT2 racer, in the form of a mid-engine R8.) Additional privateer teams deploying Aston Martins, Fords, Porsches, Ferraris, Vipers, and even a Corvette entry have swollen the category's ranks to more than 20 cars at each race. That level of competition ultimately proved irresistible to the men and women of Corvette Racing, whose hunger for a new challenge prompted a jump to GT2 earlier this year.
As with the original C5-R and the C6.R that followed, Pratt & Miller was selected to head up the development effort on the newest Corvette racer. The company was given the go-ahead for the GT2 C6.R project in October 2008, giving it only 10 months to design, develop, build, and test the car before its scheduled debut at the August, 2009, Mid-Ohio race. Fortunately, the state-of-the-art engineering tools employed by P&M allowed the team to fast-track solutions to meet the ambitious timeline. To further condense the production schedule, the GT2 test mule was converted into one of the official team entries (the No. 3 car), so only one additional C6.R was required to fill out the two-car team.
We had an opportunity to preview the new car in July, as the team conducted final shakedown runs at GingerMan Raceway just ahead of the Mid-Ohio race. As the accompanying photos show, the new C6.R's appearance is even more aggressive than that of its predecessor. Exaggerated fender bulges at all four corners and a "coke bottle" profile make the GT2 car a menacing presence from any angle. Some of this can be traced to the GT2 class rules, which require that all race cars closely follow the architecture and dimensions of their street-car siblings.
For example, the doors of the new C6.R are in the same position as those of the ZR1 it's patterned on. This is a marked departure from the GT1 car, whose doors were "pushed out" to provide a more flowing design. The team has, however, been allowed to utilize virtually the same wheel-and-tire package it employed in GT1. The center-lock BBS wheels are the same dimensions as before, but this time around are constructed of aluminum alloy instead of magnesium. Shod with the same Michelin racing tires the team used in GT1, required that the wheelwells be bulged and the bodywork extended to encompass them. But despite the new wasp-waisted look, the overall width of the car remains the same as before.
The brakes are again provided by AP Racing, but the rotors are now steel rather than carbon ceramic as on the GT1 car. (The steel rotors are required by GT2 rules, even though the stock ZR1 comes with composite brakes as original equipment.) The BBS wheels are now of peg-drive design, which is a switch from the GT1's peg-drive hub arrangement. This change was an engineering decision intended to bring greater serviceability to the package.
The front fenders have lost their distinctive louvers, but the familiar NACA ducts on the top of the rear fenders remain, providing cooling air to the rear brakes. The waterfall hood design is also carried over from GT1, and the hood itself is an easy-to-remove single-panel affair held in place with quick pins in the front (as before) and latches in the back (a deviation from the previous design). The rear hatch cover is also removable separately, as in the GT1 car, but the rear hatch area retains a floor, as in production Corvettes. As a result, removing the rear cover reveals an area that looks very much like a stock Vette's cargo space. A three-piece removable floor panel gives team mechanics access to the transaxle components and rear suspension.
Prominent in this area are the termini of a stout rollcage and the entry galleys for the fuel cells. These fuel fillers exit flush with the bodywork, just below the rear hatch window on each side of the car. This is another deviation from the GT1 car, whose fuel-fill openings were quite low on the bodywork. Although the latter location was banned by the ALMS for providing a competitive advantage, the GT1 C6.R was allowed to keep the old fillers thanks to a grandfather exemption. As a new entry, the GT2 version was not similarly exempted.
All of the GT2 C6.R's body panels are constructed from carbon-fiber in the team's composite shops, with none of them carried over directly from the street car. Because of class rules, the rear wing of the GT2 car is much smaller than that of its forebear. The new car does, however, receive a lip spoiler affixed to the trailing edge of the rear bodywork; this piece comes complements of the original-equipment specifications on the production ZR1. The front spoiler has the same dimensions as found on a stock ZR1.
The chassis of the GT2 car starts with a factory-fresh Z06/ZR1 aluminum frame. To this stock structure are welded several hard points, to which the rollbar and various other items are attached through a combination of pinning and welding. The engine displaces 6.0 liters-down a full liter from the GT1 car-and runs on environmentally friendly E85 cellulosic ethanol fuel that was developed and formulated at GM's Wixom engine plant. It's mated via a torque tube to a new transaxle gearbox provided by XTRAC, the same company supplied the previous C6.R. The new unit is about 50 pounds lighter than the old one, thanks to the reduced mass of the outside case and internal components. As before, the car's generator and air-conditioning units are driven off of the transaxle.
The exhaust system terminates on either side of the car as before; however, it now exits through a tip with a new flattened-oval shape. This change was dictated by the rocker-panel dimensions, which are shared with the stock ZR1. The round design used on the GT1 car would have cut into the floor of the GT2 cockpit, so the tip was literally flattened, while preserving its original size.
Also noticeable is the absence of side splitters, which were used on the GT1 C6.R and appear on the stock ZR1. Extending the side rocker covers to ZR1 dimensions to cover the exhaust meant no room was left for these add-on pieces. Out back, the GT2 diffuser also looks very different. It's now a flat board that runs the width of the car, instead of occupying the space between the rear wheels. Gone are the distinctive vertical fins, prohibited by GT2 rules. (Interestingly, the GT2 diffuser was actually run on the GT1 car during practice at last season's Laguna Seca race.)
Inside the cockpit, things look much the same as in the GT1 car, but all of the components have been changed to match the ZR1's dimensions. The steering wheel and gauges remain unaltered, but the telemetry has been removed to conform to GT2 rules. Every parameter on the GT1 car was monitored in real time while it circulated the track. With the GT2 car, the engineering team must wait until the car has pitted to download the information the onboard systems have accumulated.
Incredibly, the pilot of the GT2 car has no conventional gauges to scan-just warning lights to get his attention and then direct him to a digital readout. The crew in the pits can no longer advise the driver of a deflating tire, an elevated engine temperature, or any other potential problem. Rather, the driver must interpret and communicate any problems he experiences to the engineers via the radio, then make a decision as to whether a pit stop is warranted.
The remainder of the cabin is the same as before, with the conspicuous, gold-covered AC ducting and the solid rear bulkhead obstructing the driver's rear view. Monitoring what's going on behind the car takes place as before, on a small monitor mounted in the position typically occupied by a conventional rearvew mirror. The image is supplied by a small "bullet" camera mounted in the rear bodywork.
The GingerMan test found both GT2 C6.Rs circulating the track with no real difficulty. Although the engineers and drivers were still sorting out the finer details of brake bias and handling balance, all indications were that the team would be fully prepared to take on a very experienced and motivated GT2 field. The learning curve is sure to be steep, but as we've seen before, the Corvette contingent is always up for a challenge.