For most of 2009 and all the way back to the early 2000s, the Corvette Racing Team absolutely dominated the ALMS GT1 class. The team–backed by Chevrolet but operated by Pratt & Miller Engineering–had won eight consecutive ALMS GT1 manufacturers and team championships, as well as seven straight ALMS GT1 drivers’ titles–not to mention six class victories at the 24 Hours of Le Mans. Obviously, this dominant team needed a new challenge.
And it got one–the 2010 racing season was a tough one. It was their first full season in the ALMS GT class, which was formerly called GT2. Changing to the GT class threw Corvette Racing into a more competitive mix of the types of cars that the production models compete with in the showroom, and also allows a strong showroom link to the ZR1, on which the C6.R race cars are based. At a glance, most enthusiasts wouldn’t spot the difference between the old GT1 race cars and the current GT cars, but the cars’ chassis are significantly different. The GT cars have a more production-oriented body structure–including the factory framerails and a production windshield–and are required to run things like iron disc brake rotors. For Corvette Racing, that meant giving up the chassis configuration they’d won all those championships with, not to mention high-tech niceties like carbon-ceramic brakes.
Another big change was the switch from the monster 7.0-liter LS7.R engine to a unique 5.5-liter engine, dubbed the LS5.5R. Its construction was brought in-house, too. The smaller displacement resulted in a reduction in horsepower, from about 590 to around 485, while the race cars’ curb weights increased from around 2,580 pounds to 2,745 pounds.
You didn’t have to have a slide rule in your back pocket to figure out that more weight and less horsepower would drastically alter the on-track performance compared to the GT1 cars. It did–and rather than decimating the competition, as had been the case for much of the previous decade, the Corvette Racing team found itself in the fiercest competition ever.
And from all appearances, the team relished in the fender-rubbing action. Despite some challenges throughout the 2010 season, including losing two engines at Le Mans–one to internal engine failure and the other to a crash-induced loss of oil–the team never said die. The two race cars, the drivers, and crew clawed their way through the ALMS season and claimed a win at the final race of the year: the Petit Le Mans at Road Atlanta. It was a final-lap win and the only of the season, but a win is a win.
You’d think after a tough season devoid of the usual Sunday-afternoon trophy presentations, the Corvette Racing team would have rolled back to its New Hudson, Michigan headquarters demoralized and frustrated. You’d be wrong.
We were granted access to the shop a couple of days after the season-ending Road Atlanta race and found a busy, dedicated enclave of fabricators, builders, and crew members. Two days after the season-ending race, they were mentally in the 2011 season, focusing on the construction of two new GT chassis (if you’re in the market for a seasoned GT chassis, they’ll be putting the 2010 cars up for sale). It was a professional atmosphere, where everybody was focused on moving forward. In fact, there was no talk of the just-ended season, only conversations about readying the cars for an upcoming test session.
Gary Pratt and Jim Miller founded the company in 1989 that would eventually run Corvette Racing within a decade, but they were competitors in Trans Am racing before that. Pratt brought the experience to build and maintain a racing team, while Miller contributed a strong business instinct. Their collaboration has created a world-class operation that includes design and engineering capabilities beyond the racetrack.
Pratt & Miller maintains the Corvette Racing team in a gleaming, hospital-clean facility that covers about 100,000 square feet (although not all of it is used strictly for the Corvettes). Within its antiseptic walls, crew members handle the needs of the two-car team. And while engine building is handled at a nearby GM facility, all of the other aspects of the cars’ fabrication and construction are handled in-house.
Our tour of the racing shop was surprising, not for its complexity but the very opposite. It was a remarkably straightforward and lean facility. Tables, tool chests, and work benches ring the floor, but there isn’t a labyrinth of extraneous machinery. Everything that’s necessary is at hand, with nothing else to get in the way. After more than a decade with Corvette Racing under their banner, the team has got the process down to a science.
And the team definitely knows how to disassemble and reassemble a race car. During the 2010 Le Mans race, the crash that sent one of the cars into the paddock brought a flurry of activity that saw members from both Corvette crews (the other car had already expired its engine) replace the front and rear clips, make all the necessary mechanical repairs, and get the car back on the track in only 30 minutes.
With luck, they won’t have to repeat such a performance during the 2011 season. With the experience gained last season and a hunger to reclaim the checkered flags it was used to taking, the Corvette Racing team promises to make the new racing season the most exciting yet.
Special thanks to the Corvette Racing team for allowing us access into its high-tech facility. Follow the team’s progress at www.corvetteracing.com.
The lobby of Corvette Racing’s headquarters is filled with the myriad of trophies collected since it launched the Corvette Racing team in 1999. The championship-winning C5.R in the foreground was instrumental in re-establishing the Corvette’s dominance on the racetrack.
Each race car has a dedicated slot on the shop floor at Pratt & Miller Engineering. The entire facility covers approximately 100,000 square feet.
There are racing wheels seemingly in every corner of the shop. Measuring 18x12.5 inches for the front and 18x13 inches in the rear, each one takes up a lot of space. Look closely and you’ll see pressure monitors mounted on each rim.
After several years of running a nearly 600-hp 7.0-liter LS7.R racing engine, the change to the GT class (formerly GT2) meant a reduction to a new 5.5-liter engine that makes about 485 hp. Check out the elaborate air-induction system that feeds carbon-fiber air boxes.
It’s not obvious in this shot, but the C6.R has a direct link to production ZR1 Corvettes, including the frame on which the race car is built. There are other production elements, including the windshield, taillights, and more.
Compared to the previous GT1 race cars that dominated the class, the new GT-class cars are heavier, have less horsepower, and carry more production content. That’s a greater benefit in the technology transfer that influences street-bound Corvettes.
It’s all business in the race car’s interior, with safety equipment sharing space with controls and data logging tools. With all the equipment seen here, including the crisscross of roll cage tubing, it’s hard to believe the car’s race weight is less than 2,800 pounds.
Massive racing disc brakes are used at each corner. They keep cool under race conditions with elaborate ducting that feeds fresh air from the front fascia. Note the large center spindle, on which the wheel mounts with a single fastener rather than multiple lug nuts.
The body of the C6.R is based on the production Corvette ZR1, including the front fascia, although the production projector beam lamps are replaced with more conventional halogen lamps.
Crucial drivetrain parts, like this component of the Xtrac six-speed sequential transaxle, is carefully inspected for cracks or other stress that may lead to a failure on the track.
Another big change that came with moving to the GT class was replacing the high-tech carbon-ceramic disc brake rotors with conventional–and heavier–steel rotors. They’re used with carbon pads, however, for greater wear characteristics. The steel rotors are much cheaper than carbon rotors, but they are more prone to wear.
Exquisite carbon fiber details abound on the race cars, including the airbox atop the 5.5-liter racing engine.
CORVETTE ZR1 VS. C6.R GT RACE CAR
|Corvette ZR1||Corvette C6.R|
|Displacement (liters / cid):||6.2 / 376||5.5 / 336|
|Horsepower:||638 @ 6500 rpm||485 @ 5800|
|Torque (lb-ft):||604 @ 3800 rpm||not available|
|Bore diameter (mm / in):||103.25 / 4.06||103.89 / 4.090|
|Crankshaft stroke (mm / in):||92 / 3.62||80.90 / 3.185|
|“V” angle (deg):||90||90|
(mm / ci):
|111.7 / 4.40||111.7 / 4.40|
|Valvetrain:||pushrod with overhead valves, titanium intake||pushrod with overhead valves, titanium intake and exhaust|
|Valves per cylinder:||2||2|
|Cylinder case material:||aluminum||aluminum|
|Cylinder liners:||dry iron||aluminum|
|Cylinder head material:||aluminum||aluminum, CNC ported|
|Lubrication system:||dry sump||dry sump|
|Fuel system:||sequential EFI||sequential EFI|
|Throttle system:||supercharged w/intercooler, throttle body||individual runner|
|Fuel:||premium unleaded gasoline required||E85R ethanol (ALMS)|
E10 (Le Mans)
|Body style:||two-door hatchback coupe||two-door hatchback coupe|
|Drivetrain:||longitudinal front engine, rear-wheel drive||longitudinal front engine, rear-wheel drive|
|Chassis:||hydroformed aluminum chassis, composite body||hydroformed aluminum chassis, composite body|
|Wheelbase (mm / in):||2685 / 105.7||2685 / 105.7|
|Length (mm / in):||4475 / 176.2||4475 / 176.2|
|Width (mm / in):||1928 / 75.9||1996 / 78.6|
|Height (mm / in):||1248 / 49||1166 / 45.9|
|Weight (kg / lb):||1508 / 3324||1245 / 2745|
|Front suspension:||independent, short/long arm double wishbone, cast aluminum controls, transverse-mounted composite leaf spring, monotube shock absorbers, anti-roll bar||independent, short/long double wishbone, fabricated steel upper and lower, machined aluminum knuckle, coil-over multi-adjustable shock absorbers, anti-roll bar|
|Rear suspension:||independent, short/long arm double wishbone, cast aluminum control arms, transverse-mounted composite leaf spring, monotube shock absorbers, anti-roll bar||independent, short/long arm double wishbone, steel fabricated upper and lower control arms, machined aluminum knuckle, coil-over multi-adjustable shock absorbers, anti-roll bar|
|Brakes:||front and rear power-assisted carbon-ceramic disc with 6-piston front and 4-piston rear calipers, cross-drilled rotors, ABS||4-wheel disc with monoblock calipers, steel rotors and ceramic composite pads|
|Wheels (in):||19 x 10 (front); 20 x 12 (rear)||18 x 12.5 (front); 18 x 13 (rear)|
|Tires:||Michelin Pilot Sport 2|
|Michelin racing tires,|
|Fuel capacity (liters / gal):||68 / 18||90 / 23.77 (Le Mans)|
110 / 29 (ALMS E85R)