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2008 Corvette GT4 Race Car - Against All Odds

Weight And Output Penalties Make Corvette's GT4 Debut A Challenge

Walt Thurn Dec 1, 2008
Vemp_0812_01_z 2008_chevrolet_corvette_GT4_race_car Passenger_side_view 2/9

The first finished GT4 Corvette was shown at a dealer event in Mireval, France, in late February.

Production-based racing may not be hugely popular in the United States, but across the Atlantic, the Federation Internationale de L'Automobile (FIA) is fully committed to the sport. Presently, the organization produces four GT-class series-GT1, GT2, GT3, and GT4. The newest, GT4, made its debut at Silverstone in 2007. These races are held on six European circuits-Silverstone, Monza, Oschersleben, Francorchamps, Brno, and Nogaro-more or less mirroring the GT3 schedule. The difference lies in the fact that GT3 involves heavily modified cars and semiprofessional drivers, while GT4 cars are more lightly tweaked and driven by amateurs.

Vemp_0812_02_z 2008_chevrolet_corvette_GT4_race_car Chassis 3/9

In December 2007, Corvette Europe shipped a new C6 to Callaway Competition in Germany, where it was converted to GT4 specs. The car was completed in late January and weighed in at just 2,959 pounds.

No Corvettes competed in GT4 in 2007. Seeing the popularity of the new class, Corvette Europe personnel petitioned the SRO (the Stephane Ratel Organization, which administers the series for the FIA) in the fall of 2007 to have the Vette approved for the '08 season. At first, SRO reps thought the base C6 would be too fast to compete against existing entries from Aston Martin, Porsche, and BMW. But after extensive discussion, approval was granted to build a prototype GT4 Vette for evaluation.

In December 2007, GM delivered an Atomic Orange '08 six-speed coupe to Callaway Competition in Leingarten, Germany, for the conversion. The new car was inspected, and all nonessential equipment was removed. The 6.2L LS3 engine was left unmodified except for the addition of a dry-sump oiling system. Additional modifications include heavy-duty brakes from AP Racing (14-inch rotors with six-piston calipers in front, 13-inch rotors with four-piston calipers in the rear), race-spec ABS programming, cast-magnesium OZ Racing wheels, Pirelli tires (265-18 front, 305-18 rear), a HANS-equipped Koenig seat with a six-point safety harness, and an FIA-approved rollcage.

Vemp_0812_03_z 2008_chevrolet_corvette_GT4_race_car LS3_engine 4/9

The LS3 engine remains stock, save for the addition of a dry-sump lubrication system.

Rounding out the mods are a 104-liter safety fuel tank that can be refueled from either side of the car, a pneumatic jacking system, polycarbonate rear and side windows, and GM Performance Parts T1 suspension bits with adjustable antiroll bars. Although the engine is power-restricted in GT4 configuration, Callaway can boost output to 500 hp for use in non-FIA race categories. An aerodynamic body kit is available; it consists of a large front spoiler with a splitter and downforce-enhancing a rear wing. These options will be fitted to Corvettes entered in the Dutch Supercar Challenge (DSC).

The prototype was completed in late February and shipped to Mirval, France, for testing. There, GT1 C6.R driver Mike Hezemans and GM test driver Patrick Herman wrung out the new car and proclaimed it ready to race. Next, the Vette was sent to Nogaro for a GT4 "balance of performance" test by the FIA. The FIA uses this session to equalize the performance of each class entry via weight manipulation and engine restrictors.

Vemp_0812_04_z 2008_chevrolet_corvette_GT4_race_car Interior 5/9

All of the factory instrumentation is retained, including the head-up display.

The Corvette started the test session running two seconds per lap faster than its GT4 competitors. To slow it down, the FIA added 58 kg (128 pounds) of weight and an engine restrictor to reduce power from 436 to 398 hp. After successfully completing a DSC shakedown event, the car was shipped to Silverstone for the GT4 season opener.

Two races were scheduled, one each on Saturday and Sunday. When the Corvette arrived, SRO official driver Kurt Mollekens hot-lapped the car to see if the added weight and restrictor had achieved the desired effect. Finding that the Vette was still too fast, the SRO added another 50 kg (110 pounds) of ballast. It was in this configuration, with driver Danny van Dongen at the wheel, that the car qualified second fastest for Race One. (Incredibly, Aston Martins took first, third, fourth, and fifth.) Rookie driver Rogier Kroymans, meanwhile, qualified the Vette further down in the field for Race Two.

Vemp_0812_05_z 2008_chevrolet_corvette_GT4_race_car Ballast 6/9

After testing in Nogaro, the FIA required the team to add 128 pounds of ballast and an engine restrictor to the car. Here, crew members are shown hoisting the extra weight into place.

Saturday dawned cold (35 degrees F) and windy with a slight drizzle. The start of the race saw a lively battle between two Astons and the lone Corvette. On Lap Two, one of the Astons spun and hit the wall hard enough to put the race under caution. When racing resumed, van Dongen tucked in behind the leading Aston for the remainder of the race. Despite many attempts, van Dongen was unable to pass and finished 0.7 second behind the winner. Sunday's race saw a steady performance from Kroymans, who brought the Corvette safely home in the middle of the field. All in all, it was a promising debut for the new team.

Callaway Competition has the capacity to build five GT4 cars per year. Delivery will take place at Corvette Europe's Experience Centers, which will also carry spare parts for the cars. The FIA GT4 C6 carries a price tag of around 125,000 euros (approximately $192,500), while the DSC version goes for around 150,000 euros (approximately $231,000).



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