|Dodge VIPER GTS-R|
Dodge Viper GTS-R
Can a professional wrestler compete in the Olympics?
By DON SCHROEDER
It's mid-December at Atlanta Motor Speedway, sunny but 45 degrees, and the wind is blowing briskly across the infield of the big NASCAR oval. The temperature and low humidity suggest that the big V-10 engine in the Viper coupe droning around the infield track should have no problem cranking out its rated 650 horsepower, but it isn't.
Even though air is being rammed into this Viper's NACA hood intake at speeds above 160 mph, the V-10 is gasping for air. Engineers have discovered an unacceptable pressure drop across the race-prepared engine's stock air filters. "The dyno won't tell you this stuff, which is why we're here," says Viper engine chief Jerry Mallicoat.
That "we" also includes Viper engineer Gene Martindale, test drivers Neil Hannemann (the 1994 SCCA World Challenge champion) and Tommy Archer (of Archer Brothers fame on the Trans-Am circuit), and about two dozen other technicians, engineers, and supplier and team representatives. The object of their attention is the Viper GTS-R, a pure racing version of the Viper GTS coupe that will run in three upcoming endurance races: the Rolex 24 Hours at Daytona in February, the Exxon Superflow 12 Hours of Sebring in March, and the Le Mans 24-hour race in France this June.
The last time Chrysler built a serious race car was in 1970, for the Trans-Am series. Of five factory-prepared entries, the Dodge Challenger and Plymouth Barracuda took the last two positions in points. Factory racing has become much more sophisticated since then. And now Chrysler wants to road-race its Viper. But wait. A big, burly, steel-framed V-10 Viper battling the likes of the lithe McLaren F1 exoticar, which was purpose-built for track racing? Or battling the Porsche 911 GT2, with more than 30 years of factory-backed track experience? Are these guys missing a few lug nuts?
Well, yes, sort of. The idea of a Viper as a race car is every bit as bold as the idea, six years ago, of a street Viper, approved for production when Chrysler didn't have any money and couldn't even build a competitive sedan. Like the street car, the GTS-R is being developed on a shoestring budget--just a few million dollars--and in fast-forward time. There will be barely a year from GTS-R's approval to its first trial-by-fire at the grueling Daytona 24-hour in February. The changes required of the Viper to make a GTS-R are extensive. By the time we looked at the car in mid-December--merely six weeks before its first race--nearly all of the modifications had been carved in stone.
The rules that this GTS-R will initially live under--FIA's, IMSA's, and ACO's GT class--require the GTS-R to retain its original frame. Welded onto that frame is a stress-relieved, 4130 chrome-moly alloy steel spaceframe, which increases the torsional stiffness of the frame to more than 18,500 pound-feet per degree, more than double that of the upcoming production Viper coupe frame. The engine and transmission are lowered 2.5 inches and set back 2.8 inches in the frame for a lower center of gravity and improved weight distribution for racing--about 47/53 percent front/rear on the GTS-R versus 49/51 percent for the upcoming GTS coupe. Relocating the engine also allows frame cross-bracing over and in front of the engine, and it gives more clearance for the oil tank in the V-10's new dry-sump oil system.
For the engine, that's just the start. The racing V-10s, assembled by Caldwell Development, will be available in three forms. The standard "club" V-10 doesn't need many changes to make its 525 horsepower: just a racing camshaft with more lift and duration, and Borla headers. The "endurance" engine includes those changes, plus there's a velocity-stack intake manifold with ported heads, solid-lifter roller rockers, higher-rate valve springs, and chrome-moly Carillo connecting rods. Output is 650 horsepower. The "sprint" engine, at 700 horsepower, is an endurance engine with larger valves, an even more aggressive camshaft, and valvetrain changes that allow a higher 7000-plus-rpm redline. All three engines are based on the '97 block design, which was lightened and strengthened with new cast-in cylinder liners. Each optional engine will add about $30,000 to the GTS-R's expected $200,000 base price.
To boldly go where no Viper has gone before, Chrysler welcomed many original-equipment suppliers to its in-house effort. The transmission, for example, is a racing version of the Viper's Borg-Warner T-56 six-speed. The rear differential is a big Dana 60 with an aluminum case, specifically designed for the Viper GTS-R's tremendous torque (more than 650 pound-feet on the optional engines). The shock absorbers resemble Indy-car Konis, the steering rack is the Viper's stock TRW with revised valving, and the brakes from Brembo are whoppers--eight titanium pistons per caliper at the front, four-piston calipers at the rear, grasping either carbon-fiber or cast-iron discs. Michelin stepped in with custom Pilot SX racing slicks.
There's also a Tilton carbon-fiber triple-disc clutch and eight-pound flywheel (versus 32 pounds for the stock Viper). The center-lock three-piece BBS wheels have cast-magnesium centers. Goodyear racing tires will also be tested and offered.
All of this is wrapped up not by the Viper coupe's 350-pound resin-transfer-molded body, but one done completely in carbon fiber by Indy-car chassis builder Reynard, for a 200-pound weight savings. The body sports a biplane-type rear spoiler that increases downforce, although that will be changed to a single spoiler due to the sanctioning-body rule changes.
Nice résumé. But does it work? Chrysler wouldn't allow us behind the wheel to answer that question because the GTS-R being tested was the only one in existence. With the program timing already behind schedule, trashing the mule would mean . . no program.
But we're sure that it has no problem going, stopping, and turning. At Sebring, Chrysler did some preliminary tests with our equipment and one of their drivers. With a stock transmission, an early endurance engine, and a lousy launch, the GTS-R still leapt to 60 mph in only 3.8 seconds. It continued accelerating as if a Saturn V booster were strapped to the roof: 100 mph in 7.1 seconds, the quarter-mile in 11.5 seconds at 132 mph. Top speed should be over 200 mph, a velocity the car could reach at Daytona or Le Mans.
Despite not being optimized for such a dainty task, the brakes can haul the 2910-pound Viper from 70 to 0 mph in 148 feet. Around one 140-foot-radius curve, the GTS-R was managing 1.90 g of grip, with negligible downforce from the rear wing.
As for its ability to get around the track, that's another story. The team has been track-testing frantically for a number of months, undeterred by weather, part failures, or even hawks crashing through the windshield at 140 mph (at Road Atlanta). At Sebring in early December, the car was understeering excessively at speed, the rear end was
At Sebring in early December, the car was understeering excessively at speed, the rear end was bouncing too much, the shock valving was all wrong, and the car was too hot inside. We asked 1995 Le Mans winner Andy Wallace, sitting in the cockpit after testing, if the GTS-R was fun to drive, and there was a pregnant pause, the result perhaps of years of talking to automotive writers. "It will be," he replied. Another pause. "When it's right, it will be fantastic fun," he added. Even the ever-smiling Martindale, putting in six 12-hour days a week as engineering chief since the GTS-R was approved, seemed weary.
And there was already good news. Driver Hannemann says the GTS-R's handling is quite forgiving--a relief from a car so closely related to such a brute-force street car. Just a few weeks later at Atlanta, the GTS-R had improved considerably. The problems at Sebring had mostly been solved, and the emphasis was now shifting toward driveline durability. "On a scale of one to ten, at Sebring, I'd say we were at four. Here at Atlanta, I'd call it a six or seven," said Martindale.
Engine guru Mallicoat was more smiles, too. The engine labs were reporting little wear from a recent teardown of the development engine. Furthermore, the motor was running well with relatively lean air-fuel ratios, meaning the GTS-R's Achilles' heel--uncompetitive fuel economy--was being improved. More promising were the lap times at Atlanta of under 1:19, exceeding the goals set by the team for the first time.
Chrysler intends the first four GTS-Rs (built at the company's new Conner Avenue assembly line in Detroit) to go directly to two racing teams: Canaska-Southwind Motorsports in Toronto, for the Daytona and Sebring events, and ORECA S.A. of France, for Le Mans. Assuming those races go as planned, the company will then offer between 30 and 50 GTS-Rs at an expected base price of $200,000, roughly the same as the Porsche but a steal compared with the nearly $1.1-million racing McLaren F1 car. Chrysler plans to sell most of the cars to racing teams. Second priority will be car collectors who want a piece of history. Good history, the company hopes. For the GTS-R to even finish at Daytona would be an accomplishment.
Critics have already tarred Chrysler's efforts with its still-young sports car as quixotic, but that's a bit like slagging the fat guy at the gym. The GTS-R is a remarkable display of corporate determination. Even if it fails to make it out of the pits, the engineers have already learned some lessons as a result of this program that they will apply to the 1997 Viper. The stock '97 heads will be derived from the GTS-R's, for example, and the block design has already been strengthened by what the team has learned.
One thing's for sure: Many eyes will be on this Viper in the next few months, and for once it won't be because of that hot curvy body.