Chevrolet Corvette C6.Rs - Behind The Scenes In GT1

An Inside Look At Corvette Racing's Preseason Preparations

Dr. Greg Johnson Sep 1, 2008 0 Comment(s)
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Truth be told, Corvette Racing's '08 racing season actually started early last year. The C6.Rs designated for competition for '08 were finalized by Sebring '07 and, for the most part, sat idle at the Pratt & Miller compound for the next several months. (One of the cars-this year's No. 4-was used for display purposes throughout the '07 race campaign.) While both cars ultimately lost a few components to late-season parts pirating, it didn't take much work to get them battle-ready for the coming year. After three seasons running the current C6.R architecture, the team has the particulars of car setup pretty well in hand.

Practice Makes Perfect
Tire testing with Michelin has become a fixture in the Corvette Racing schedule. Engineers from both the team and the tire manufacturer closely evaluate compounds and configurations during the months leading up to Le Mans. February's preseason test regimen at Sebring is especially intense, with both the No. 3 and No. 4 car crews in full attendance. The team sets up shop in the paddock, and the cars circulate the track for three to four laps at a time before coming in to their respective transporters for service. Tire or tire-pressure changes are made, and the cars are sent out again. This routine goes on all day, with only a brief break for lunch.

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All of the Corvette Racing drivers are present, including the third-stint pilots used to spell the regulars at endurance events such as the 12 Hours of Sebring and the 24 Hours of Le Mans. They all take turns behind the wheel, just as they would in an actual event, though the exchanges tend to be a bit more leisurely than in the heat of competition.

Going West
One of the season's more notable personnel changes can be found on the No. 4 car crew. The team has a new chief for 2008-Mike West. "Westy" is a longtime member of the Corvette Racing family, having served on the No. 3 car crew and as a mechanic in the shop. Although No. 4 has been under the stewardship of Ray Gongola for years, Gongola recently assumed a greater role at P&M's New Hudson, Michigan, facility and won't be traveling as much with the team. Despite West's formidable rsum, he's well aware that a change of this magnitude requires some getting used to for everyone involved. For that reason, the No. 4 team treated many of the test session's stop-and-go intervals as if they were actual, in-race pit stops.

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A Tire-Some Routine
A single Michelin engineer is assigned to each of the cars over the course of the three-day tire test. When "his" car comes in from the track, the engineer checks pressure and heat across the tread face of each tire. He's then directed by another Michelin engineer-this one monitoring conditions on track-to either change pressures or switch to a different tire.

Interestingly, the team and driver never know exactly what they're getting in terms of tire setup. Their job is to go out and give the car whatever push the Michelin folks are asking for, be it three hard laps, two warm-up laps followed by an all-out blitz, or something else. The Michelin reps then evaluate a number of parameters to determine the effects of the test procedure. Their evaluation also incorporates valuable "seat-of-the-pants" impressions from each of the drivers. With that done, the data are spirited back to Michelin headquarters, where development engineers use them to devise ever-more-competitive tires for the C6.R.

For many on the team, the day is characterized by monotonous, albeit hard, work. They wait for the car to return to the transporter, jack it up on air-driven stands, evaluate and/or change the tires, drop it down, and send it out again. This drill is repeated over and over again throughout the day, occasionally punctuated by unforeseen mechanical problems. At Sebring, for example, both cars suffered transaxle failures, forcing the team to take out the damaged XTRAC-built units and install replacements.

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Feeling Green
For 2008, the Sebring test session marked the team's first on-track evaluation of the C6.Rs' new E85 fuel. While the ethanol blend offers reduced emissions and is a potential public-relations coup, it also presents some interesting challenges. When alcohol burns, it releases more energy than gasoline, thereby generating greater horsepower per unit of fuel. The flip side is that more fuel is required to cover the same distance, as compared with the current VP100 race gas. In other words, fuel consumption goes up, and fuel mileage goes down.

To compensate, the team is allowed to use a larger fuel tank. But as of this writing, the ALMS hadn't decided just how big a tank the cars will get. The current tank holds 90 gallons, but most agree that an increase to 100 gallons or more will be needed to compensate for the disparity in fuel economy. Unfortunately, the C6.Rs are configured to allow a maximum fuel tank size of just 102 gallons. Practically speaking, the cars simply aren't capable of carrying any more fuel than that without major architectural revisions. If more-frequent refueling stops are required as a result, the Corvettes will be at a significant competitive disadvantage.

Running the Vettes on E85 may present other difficulties. Alcohol can play havoc with the rubber seals found throughout the cars' fuel systems. Other race cars that run methanol fuel (Indy cars, for example) must have their fuel systems completely purged at the end of every day. Gasoline is placed in the system overnight, then drained the next morning and replaced by the alcohol blend-a tedious task, at best.

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Corvette Racing didn't experience any seal problems during the tire test, but by the time the cars made it back to P&M the following week, they were hemorrhaging fuel. It seems the ALMS had decided to spec the new "E85 fuel blend" at 62 percent ethanol and 35 percent toluene. During dyno testing, the Katech crew was delighted to find that the toluene-heavy mix caused no problems for the engine, and actually increased horsepower by about two percent (roughly 12 additional ponies). But one thing no one could foresee was that once the toluene was fed into the fuel system, it literally dissolved the glue holding the C6.R fuel cell together.

The upshot of all this was that Corvette racing elected not to run E85 for the Sebring race, returning instead to last year's 90/10 blend. It, however, use a modified E85 formulation for the St. Petersburg race a few weeks later, encountering no mechanical hiccups along the way. Based on the C6.R's dominating performance in that contest, the team emerged confident that the revised ethanol mixture is fully compatible with all of the C6.R's fuel-system components.

Corvette Racing's New Look For '08
For 2008, the Corvette Racing C6.Rs have adopted a tough new mien. The most obvious change is the black racing stripe running the length of the cars. The stripe, known as the "Jake Rake," is said to simulate the team's unofficial skull mascot scraping his teeth over the car. The rest of the cosmetic tweaks are similarly menacing: black wheels, black on the rocker panels, a blacked-out rearend, and black in the headlight buckets. Taken together, the alterations make for a worthy update of a classic design. It's just as well: With no serious class competition in GT1 for the second year running, Corvette Racing will need to do everything it can to stoke fan interest.

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