2007 Petit Le Mans Race - Atlanta Braved

Fresh Competition And An On-Track Dustup Can't Stop Corvette Racing At The 10th Annual Petit Le Mans

Dr. Greg Johnson Mar 1, 2008 0 Comment(s)
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In October, race impresario Don Panoz and the American Le Mans Series cele-brated their 10th year running the Petit Le Mans enduro. The race is designed to test the strength and speed of Le Mans-spec cars over a 10-hour span or 1,000 miles, whichever comes first. Road Atlanta is the home track for the ALMS, and organization officials are rightfully proud of the way this event has flourished over the last decade. There has been a continued effort to improve the track itself as well as the support facilities for fans and competitors alike. Coupling this with a knockdown, drag-out fight between world-class racing cars brings the fans in droves.

The Corvette C6.Rs had already taken a step toward on-track comfort by attending a tire-testing session held at Road Atlanta two weeks earlier. Not only did that give them a good feeling for the new track surface, it also seasoned the roadway by laying down a significant coat of fresh rubber. Consequently, the Corvettes looked pretty good on the Thursday practice day, which included a two-hour night session.

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The rain was hitting off and on all day, and it struck again during the evening practice. The Corvette team elected to dodge most of the wet conditions and call it a day, taking the cars into the garage as soon as each of the drivers ran the three laps required to be certified for driving duties during Saturday's race. The only hiccup experienced was a faulty alternator suffered by the No. 4 car. That situation was quickly remedied, and the car was prepared for qualifying the next day.

Friday's schedule included a morning practice and a qualifying session in the afternoon. Track conditions had changed, as a thorough washing the previous evening had stripped away all the fresh rubber laid down over the last few weeks. The teams had to start from scratch on their racing setups.

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Qualifying also proved interesting, as competition in the form of a Maserati MC12 turned up to challenge the Corvettes in GT1. The Doran Racing Maser ran strong from the outset and even bested the Vettes to take pole position for the class. Was it possible the Corvette boys had finally found some legitimate class competition?

Corvette Racing protocol for endurance races (Sebring, Le Mans, and Petit) is to change the engines and gearboxes after qualifying, a process that pretty well occupies the crew until the morning of race day. Morning practice usually involves a 30-minute lapping session to be sure the newly replaced powertrain parts are functioning as expected.

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In an uncharacteristic pit-stop miscue, Olivier Beretta put the No. 4 car into Reverse and applied power as the Vette was dropped down off the air jacks. Everything but Beretta's ego seemed to escape undamaged, but the team was forced to pull the newly installed transaxle, disassemble it, and inspect the internals to be certain.

Highlights of the prerace ceremonies included a special performance of the national anthem by C6.R driver Johnny O'Connell's 10-year-old daughter, Kelly. Proving that the ability to perform under pressure is an inherited trait, she reeled off a flawless rendition of the song in front of the more than 100,000 spectators.

The Petit race starts at 11:15 a.m. and is scheduled to conclude by 9:15 p.m. With the recent improvements to the track surface and the increasingly pitched battle between the prototype Audi R10s and the Porsche Spyders, the event was not expected to run the full 10 hours. In fact, there were prerace predictions by Road Atlanta's staff that the race would end before 8:00 p.m. Rain proved not to be a factor, but the intensity of the on-track action eventually took its toll.

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When the green flag dropped, the Corvettes quickly picked off the Maserati, putting their only GT1 competitor in seven months well behind them. The No. 3 car, with Jan Magnussen driving, was running first in class with Oliver Gavin following in the No. 4 Vette. This is a long race, and it behooves everyone to settle into a groove for the duration. However, the P2 class is full of anxious young men hoping to establish a presence on the racing scene.

Magnussen got caught up in the fray as he crested the hill above Road Atlanta's famous esse complex and picked up speed entering the quick, right-left-right-left sequence. There is hardly room for one car here, let alone two, but Bryan Herta, in the No. 26 Team Andretti Green P2 Acura, pushed the issue and tried to pass Magnussen anyway. Contact was certain, sending the Corvette off course. It hit the wall on the left, was tossed into the air sideways, and came down hard against the safety barriers. It was a major hit, crushing in the left-front corner of the C6.R and tearing off the front bodywork. Magnussen was able to climb out and walk away without injury, but the car was done for the race.

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Herta was black-flagged and assessed a 30-second penalty in the pit lane for avoidable contact, but this was of little consolation to the dejected No. 3 car crew. The premature exit was particularly tough on O'Connell, whose streak of 58 consecutive starts came to an end in Atlanta.

The next two hours saw a succession of yellow flags. As soon as the course marshals could clear the track and restart the race, another full-course yellow was thrown in response to yet another accident. (The race ultimately experienced a total of eight full-course cautions.) This levied a toll on equipment and ended speculation that the event would finish in record time. The No. 4 C6.R continued to pace GT1, with the Maserati struggling to stay seven to nine laps behind the Vette.

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At about one hour from the end, the Maser, with Andrea Bertolini driving, veered off the track and slid helplessly along the concrete front-straight wall, ending its day. (With over 70 percent of the race completed, the team held on to an official Second Place finish.) The No. 4 Vette cruised home under an 8:35 p.m. checkered flag, taking a very lonely First in the GT1 class. The win secured the series class championship for the No. 4 driving duo of Oliver Gavin and Olivier Beretta.

In contrast, the R10 Audi of Dindo Capello and the Porsche Spyder of Roman Dumas staged a down-to-the-wire duel reminiscent of their clash at Detroit just three weeks earlier. Traffic posed a greater problem for the Porsche driver this time, and he was never able to overtake his Teutonic rival. The Audi team prevailed, and the two cars finished First and Second overall.

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The Story Behind The LS7.R
By the late '90s, Herb Fishel and the rest of the GM Racing crew were ready to raise the Corvette banner at the legendary 24 Hours of Le Mans. But because GT-class rules required strict adherence to the specifications of the street-going model, structural modifications to the car would be severely limited.

Fortunately, there were other areas in which performance and durability improvements could be made. One of those areas was engine development. Corvette Racing partner Pratt & Miller went to Katech Engineering to help achieve their goals for the nascent race car's powerplant.

Katech had a long history of working with GM on other projects, so the new endeavor was a natural collaboration. According to John Rice, a GM engineer at the time, it all began with a "what if" scenario regarding the viability of entering a Corvette race car in Le Mans. That started the wheels turning, and by 1999, Corvette Racing had a C5 racer sporting a race-bred 6.0L LS6.

Katech massaged the powerplant as best it could to optimize performance and durability over the race's 24-hour duration. Still, Corvette Racing's debut at Le Mans that year was less than auspicious. At that time, the reigning force in the GT1 class was the Dodge Viper. With 8 liters of displacement and a couple of years experience competing at Le Mans, the Vipers were simply too strong for their crosstown rivals. For the following year, everyone at GM and Katech went back to the drawing board and concluded that a 7.0L configuration could give the Dodges a run for their money.

Despite their identical displacements, the racing and street versions of the LS7 have very little in common. After all, the production engine has to start consistently in subzero temperatures, keep its cool in stop-and-go traffic, and exhibit flawless driveability throughout its long service life. By contrast, the race motor is never started until fluid temperatures have reached 100 degrees (F), is hammered relentlessly at all times, and is designed to last for a finite time period-be it 24 hours at Le Mans or 2 1/2 hours on a street circuit like Detroit.

When the bare-block casting is received at Katech, technicians immediately cut off the bottom portion just beneath the crankshaft center line. This has the benefit of significantly lightening the engine-a fully dressed LS7.R weighs in at about 300 pounds-while also lowering the overall center of gravity of the race car.

The bottom sump cover, which is bolted to the crankcase, is then fitted with the lower halves of the crankshaft-bearing shells. Therefore, when the cover is bolted on the case, the bearings that the crankshaft rides on are also bolted in place. This makes checking bearing tolerances a little more difficult, but Katech personnel have mastered the art of reaching in through either end of the case to do the job.

To get as much power out of the race engine as possible, the engineers at Katech and GM have developed fuel/air mapping sequences that optimize each cylinder independently. Additionally, engineers can monitor in real time exactly what is going on in the engine while the car is on track. When the car comes in for a pit stop, the crew can plug into the car's computer-management system and change the mapping sequence if necessary. John Rice, now retired from GM and working for Katech, says the crew usually has three different mapping sequences to choose from at any given time.

Since taking on the sports-car racing scene with the C5-R/C6.R, Corvette Racing has established ALMS records for the most GT1-class race wins (C5-R: 31, C6.R: 24) and the most wins in any class (55). Astonishingly, the team has lofted the GT1 winner's trophy at Le Mans five times in the last seven years. With a track record like this, it's no wonder the LS7.R was named Global Motorsports Engine of the Year in 2006.

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