Door to Door with SRT Viper

March 6, 2014

Door to Door with SRT Viper

March 6, 2014

viper_3_6_14When the checkered flag fell on the Rolex 24 at Daytona on January 26, Team SRT – that stands for Street and Racing Technology – had much to celebrate, much to lament. The last time the Viper team was at Daytona, in 2000, it was branded Dodge, instead of SRT. And unexpectedly, the car won overall, beating all the exotic, faster Prototype entries that either broke or crashed, this being quite early in the Prototype era.

The American Le Mans Series, which is where the SRT Vipers have been racing, merged with the GRAND-AM Series, and beginning at the Rolex 24 at Daytona, the combined field raced under the auspices of the TUDOR United SportsCar Championship. With a combined schedule, too, this meant that the Viper would be racing again at Daytona, followed up by the Mobil 1 Twelve Hours of Sebring.

viper_sebringDaytona, then, was a learning experience for the two-car SRT Motorsports Viper GTS-R team. And with a solid third-place finish for one car, the race had to be judged a success. But given the fact that both Vipers led for much of the 24 hours, it simply primed the pump for Sebring.

At Daytona, the number 91 Viper was driven to the podium finish by Dominik Farnbacher, Marc Goossens and Ryan Hunter-Reay. The team car, number 93, finished sixth in class with drivers Rob Bell, Jonathan Bomarito and Kuno Wittmer, each one leading at least a lap in the race. But just short of halfway, that car was forced into the wall coming out of the pits and required a lengthy run of pit-side repairs to fix the front end.

Even the number 91 wasn’t immune from problems – a power steering hose ruptured, requiring a 15-minute repair that likely cost the car a win, dropping it 12 laps behind the leader. At the end, they had made up all but four laps.

Bottom line, though: Team SRT had run well, and both cars survived the race relatively intact. On to Sebring, right?

Well, not exactly. Even with two intact, operable cars, much work was left to do before returning to Florida for the grueling 12-hour race on Sebring’s ancient, bumpy pavement – a perfect warm-up and shake-down for the 24 Hours of Le Mans.

So what happened in the 48 days between Daytona and Sebring?

“Basically,” said Russ Ruedisueli, head of SRT and Motorsports Engineering, “we completely rebuilt both cars, from the ground up.”

For the number 91, that rebuild was delayed a bit – the car was transported, in its exact race-finishing condition, grit and grime intact – to the Chicago Auto Show, where it was displayed next to its street-going counterpart, one sure way to demonstrate the “technology transfer” that keeps manufacturers deep into sports-car racing.

viper_sebring_testLike the new Chevrolet Corvette C7.R, the Viper’s arch rival, the racing versions are considered test beds for new technology, and a way to gauge reliability under the most trying conditions. Meanwhile number 93 was shipped back to Sebring for a two-day test, using part of the Daytona package, including the same engine.

A complete rebuild is necessary for two reasons – Daytona is the longest race on the SRT Viper’s schedule, and Sebring is the most demanding. “Sebring is the toughest track on a car,” said Bill Riley, vice-president and chief engineer of Riley Technologies, SRT’s partner in building and racing the Viper. “Per hour, it’s the toughest place on a car without a doubt. As far as sports car racecar tracks – this is the toughest.  Sebring will prove your car. Le Mans will prove your engine. Daytona is between the two.”

The cars are completely dismantled, Ruedisueli said. After a 24-hour race, the engine is replaced by one that is either new or rebuilt – on shorter races, an engine can run three events between replacement. “We changed radiators, hoses, all electronics – we look at the data we gather during the race to see if there were any issues, and we maintain a checklist at the track of items we need to improve.”

The transmission and differential are rebuilt, and the carbon bodies needed repainting – “There is so much sand at Daytona, that it just sandblasts the paint during the race,” Ruedisueli said.

Rules-wise, IMSA, the sanctioning body, tries to maintain a “balance of performance,” in the Viper’s GT-Le Mans class, with the Corvette C7.R, Porsche 911, BMW Z4, Ferrari 458 and Aston Martin Vantage. After Daytona, IMSA put a smaller air restrictor on the Viper’s V-10 engine, added some mandatory weight to the car, and reduced the size of its fuel cell. Those changes had to be incorporated into the rebuilds for Sebring.

The suspension is also rebuilt or replaced, a critical factor for this race. One of the few things the tight rules allow is different shock absorbers and springs, tailored to each track, and at Sebring, that’s important.

“We’ve raised the ride height, because the track is so darn bumpy,” said Ruedisueli. “At Sebring, grip is everything.” SRT, like every other GT-Le Mans competitor at Daytona, chose Michelin as the tire partner; in the only TUDOR Championship class that allows racers to choose whatever brand of tire they prefer.

The Twelve Hours of Sebring will have an enormous field of 66 cars – including the two GT-Le Mans Vipers. “We’ll be ready,” Ruedisueli said. “If you think we have something to prove after Daytona, well, you’re right!”

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