Corvette C6.R GT Racecar

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http://www.corvetteracing.com



More Photos Here:
http://www.corvetteracing.com/pictures/c6r_intro/


"The Corvette C6-R is the best sports car we've ever built and it has been our privilege to develop it alongside the new Corvette Z06," said Harry Turner, GM's group manager for road racing. "History will remember the C5-R as one of the best sports racing cars of all-time and we�ve set the bar high for the C6-R. With the new C6 chassis and body structure as our starting point, we're already ahead. We left no stone unturned in the development of this new car and we are looking forward to racing it in front of the world in 2005."

Like the C5-R before it, the Corvette C6-R starts from production roots: the same hydroformed frame rails that roll down the assembly line at the Corvette plant in Bowling Green, Kentucky are sourced for the structure of the race car. With the new C6 production model measuring shorter in overall length (but with a longer wheelbase), race car engineers faced a new set of numbers in which to achieve their goals to make the car faster on the 180-mph Mulsanne Straight at Le Mans and other high-speed circuits.

"At first glance, the shortened front and rear overhangs on the C6 would seem to present a challenge in developing a racecar with maximum aerodynamic downforce," said Steve Wesoloski, program engineering manager for Corvette Racing. "However, the low drag features on the C6, such as the sleek body and flush headlamps, lend themselves to an easy task of converting the production design into a low-drag race car."

Adding a rear wing and a front splitter enabled the team to develop a package that achieves a lift-to-drag ratio better than that of the C5-R. Through a combination of Computational Fluid Dynamic studies and on-track testing, the end result will be an aerodynamically balanced package, tunable to the low drag demands of Le Mans or the high downforce requirements of Mosport.

The phrase "technology transfer" has never been more appropriate than when used to describe the matched set of Corvette C6-R and Corvette Z06. Lessons learned on the track have benefited the Z06, just as GM's vast resources have enriched the C6-R race car. Both cars are powered by 7-liter small-block V-8 engines with dry-sump lubrication systems, CNC-ported cylinder heads, titanium valves and connecting rods, forged steel crankshafts, and plate-honed cylinder bores. While the components and specifications of the street and competition engines are tailored to their specific environments, the thought process behind them is identical.

Corvette Racing dominated the American Le Mans Series for the fifth straight year in 2005, but it wasn't easy. The introduction of the new Corvette C6.R race cars, the emergence of powerful new rivals (i.e. Aston Martin), and the impact of new rules shaped the season for Chevrolet's two-car factory team.

The yellow Corvettes raced to 10 victories in 11 starts, including the team's fourth win in the 24 Hours of Le Mans. Chevrolet won the ALMS GT1 manufacturers championship for the fifth consecutive year, and Corvette Racing swept the drivers, team and pit crew championships. When the checkered flag fell on the victorious Corvette C6.R of newly crowned GT1 champions Oliver Gavin and Olivier Beretta at the ALMS season finale in Monterey, Calif., it marked Corvette Racing's 45th win in international endurance racing and the team's 31st 1-2 finish.

New Velocity Yellow paint wasn't the only trait that distinguished the Corvette C6.Rs from their championship-winning C5-R predecessors. In fact, the C6.R was a different animal under its carbon fiber skin.



"There is no question that we had a steep development curve with C6.R," said Fehan. "We developed this car for a year before it appeared in public, so it had many miles of testing before its first race at Sebring. You only have to look at the differences between the C5-R and the C6.R - a 1-inch shorter wheelbase and 5-inch shorter body - to appreciate how much work had to be done. You can't just reskin an old car and expect it to win."

The changes in the sixth-generation Corvette's exterior were striking: a single, large grille opening for the engine air intake, radiator, and brake cooling; flush headlights for better aerodynamics; and a smaller, sleeker shape that reduced drag. But there were invisible changes as well.

"Both the chassis and the aerodynamic package changed considerably," explained Steve Wesoloski, GM Racing road racing group manager. "The new regulations required more extensive use of the production car's chassis structure, retaining items such as the central drivetrain tunnel, the windshield frame and the rear bumper. These requirements affected the C6.R's weight distribution, and we had to understand how that change influenced its on-track performance. We also introduced new low-friction suspension attachments that made the car quicker to react, and that required the engineering team to make corresponding changes in the setup throughout the season."

"When you introduce a car with shorter front and rear overhangs, you have to understand what that means for the aerodynamics," Wesoloski continued. "We did a lot of CFD (computational fluid dynamics) analysis before the start of the season, but until the car is actually running on the race track, you can't accurately determine the effects of changes in ride height on the aero balance of the car. There were adjustments made throughout the season as we learned more about the characteristics of the C6.R in actual race conditions."

There were also new horses under the hood as well. The 2005 season saw the introduction of the LS7.R racing engine, a further refinement of the GM small-block V-8 that has been the world's most successful production-based racing engine over a span of 50 years. Lighter and more powerful than previous Corvette powerplants, the LS7.R shares technology with the production 505 hp LS7 the powers the 2006 Corvette Z06 supercar.

"While the small-block V-8's fundamentals and configuration remained unchanged, the LS7.R's internal components were designed to reduce horsepower losses due to internal friction and to reduce rotating mass," Wesoloski revealed. "We took a considerable amount of weight out of the engine, helping the balance of the car while also improving performance. Comparing the lap times at Road Atlanta from the race in April to Petit Le Mans in October, much of the improvement in lap times was the result of six months of engine development."

Corvette Racing's championship-winning C6.Rs will be replaced by two new cars for the 2006 campaign that begins at the Mobil 1 Twelve Hours of Sebring on March 18. The team's to-do list for next season includes continued refinement of the underbody aerodynamics and engine specifications as permitted by the series regulations.

"Just when I think the Corvette team has done all that can be done, they surprise me," said GM Racing director Mark Kent. "I just can't wait to see what they do next, and I'm glad that our racing efforts will be part of making the next generation Corvette even better."

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Note the change in rear diffuser configuration from the photo from the introduction (top) compared to this one. There are 11 vertical slats instead of the PR shot from the intro that shows four.
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Lovely night shot of a Saleen chasing the 'vette in Laguna Seca


Starting lineup at the 2005 LeMans Race
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http://www.racecar-engineering.com

With a new C6 road version of the Corvette on the market, Chevrolet brought its C6R to Le Mans for the first time and not all the road car developments have been a benefit to the racing version. Although the new car's wheelbase has been stretched by 1.2 inches from 105.5 to 105.7, the overall length is five inches shorter considerably reducing the overhangs with a resulting downforce penalty. While it was possible to retrieve much of that downforce be extending the front splitter to the legal maximum, it would have shifted the centre of pressure too far forward. Instead the team opted for less overall downforce in pursuit of a better balance.

The road car version has many hours of CFD and windtunnel work to reduce drag benefitting the racing version which has to follow the same overall shape. Consequently the C6R has an almost identical lift to drag ratio as the C5R - between 2.1 and 2.2:1. The challenge for the team was to recover as much rear downforce as possible without creating more drag. One ploy was to run with side windows, something the team normally only did at Le Mans and other very fast circuits. The issue here was not drag but keeping the flow onto the rear wing smooth. The closed side windows generate less turbulence and feed a more laminar flow to the aerofoil allowing it to operate more efficiently. With this and a heavily straked rear diffuser, the aero balance was shifted from 50 percent front to a more ideal 43 per cent front.

Remarkably he C6R does not use the aluminium chassis of the Z6 road car for a number of reasons. Firstly a steel chassis behaves more predictably in a crash and is easier to repair. Also, it allows an integral steel roll cage to be fitted very easily. With an aluminium chassis the attachment points would have been more complex and added considerably to the weight. These factors plus the fact the car can easily be built underweight and the chassis is low in the structure makes steel preferable. While designing the C6R, the team was obliged to keep more of the sub structures, including bumper supports and the windscreen frame, than on the C5R adding considerable weight ultimately reducing the total ballast by 60 per cent.
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Drags, Circuit, Solodex, Rally, Karting, the Shows, the Girls, the Car you drive...
ZORCERs done know... the speed lifestyle magazine in the Islands, ZORCE
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Oh Yeah! Feel the Rush, it's like... WOW!
May the (Mass x Acceleration)-F+Z be with you...