The 1987 GTO Championship was a major step towards costs escalation. Cars were no longer production GT derivatives, they had become true race cars, with full featured tubeframe chassis. The GTO category had become the battleground for the manufacturers and the fiercest one for cars with fenders. Sandwiched between GTP cars and GTUs, it was the home of the big bangers. Cars ranged from 3,0 to 6,0 Liter displacement. At first sight, cars looked similar to their showroom counterparts, in order to keep the manufacturers involved, which was of course one of the key point. "Racing allows us to showcase the durability, handling and speed of our high-performance cars", said Les Unger, Toyota Motorsport Manager.
Copyright Michael Crews
One thing appeared for sure, Toyota's involvement in IMSA was quite obvious, and the backing from the factory was now clear. That became obvious to many people by the season end when Chris Cord wrapped up the Championship on his Toyota Celica Turbo. The first step towards eligibility was recognition by the IMSA board of rules. In fact, nearly every manufacturer was able to produce a car that fitted in the 3,0 to 6,0L limit. Whether your car was rotary powered, turbocharged or not, fuel injected or not, was V6, V8 or Flat 6 powered, it was quite sure to be eligible, and John Bishop would swing his gate wide open to any new team willing to enter the fray.
From a technical point of view, nearly everything could be modified. A front drive car could be converted to rear drive, the transaxle could be moved to the rear. Steering, braking and suspension could be modified to the constructor's wish. Transmission choices were wide, as well as chassis preparation. A combination rollcage had to be fittd into the confines of the chassis while a rollcage stiffened the the whole bodywork. Bigger engines could be used as long as the powerplants were available at your dealer's shop. Every part which was to be used for improving the engine's power had to be submitted to IMSA for approval, but it had now become an easy task to perform. The stock number of valves, ports and spark plugs had to remain unchanged. The cars had to retain their original shape, dimensions, contour and orientation. Lowering the car was admitted with rocker panel to road dimension up to three inches. The cars could be widened up to 79 inches. Body materials were unregulated, and to the builders' likings. Many teams came to use removable fiberglass to cloak their chassis components. The roof panels was usually the only remaining stock part. IMSA had devised a carefully well balanced set of rules, which used a displacement versus minimum weight formula in order to equate everyone chances.
Copyright Michael Crews
For example, a 3,0L powered car had to weight 1900 pounds while a 6,0L could not weigh less than 2700 pounds. Cars which were 2 valves turbocharged were added 15% weight while 4 valves turbocharged cars were added 20% weight. Many top teams used an electronical fuel injection to good advantage. Aerodynamic refinement was the name of the game, and testing in wind tunnels were now common place. The search for minimal drag, stability and high speed improvement was relentless. No ground effect tunnels were allowed.
IMSA allowed wider modifications to the cars. But this new set of rules, which moved away the cars from their original shape, seemed to move the series itself to light years from the original purpose. Gone were the days where you could race your Camaro or Mustang with a few bucks. The cars, which retained the GT name, were in fact true disguised prototypes, and not any private team could afford them.
But when you stripped them down, you were struck by what you could see. Have you ever seen a Chevrolet Camaro with a March Indy car racing suspension, a carbon fiber tubeframe chassis and a 600 hp V8 engine? For sure you didn't, and it was now the usual machinery you had to use to run for the GTO class win. Bob Carson, head of Peerless Racing, estimates $1 300 000 have been spent for a full season. Not so far as a GTP program! Three types of engines were to be used on the wildest Camaro ever built. A V8 5,0L on most courses, a V6 5,0L on the street courses and a V8 6,0L in the enduros. The ultimate sophistication was to build an underweight car and add some ballast that you move around the car according to the track you were racing at. And it worked : Jack Baldwin threatened the Ford and Toyota fleets. He won at Firebird, Sears Point and Columbus.
Copyright Kirk Hoffman
At Protofab, cars were not less sophisticated and drivers such as Greg Pickett, Wally Dallenbach or Tommy Riggins were hired. The season had begun with a win at Sebring. At the end of the season, a new lightweight Corvette was introduced and appeared to be quite efficient, with two seconds at Summit Point and Road Atlanta. Roger Mandeville had a three rotor Mazda RX7 given for 500 hp.The car had the same powerplant you could find on the 757 prototypes running at Le Mans. The chassis was designed by Bob Cuneo and the car was tested at the Lockheed wind tunnel, it was worth 305km/h on the straights.
Ford was represented by Roush Racing whose cars were ageing ones. The future of the Detroit iron was named Merkur. The cars were successfully tested and run in the Trans Am series as Scott Pruett and Pete Halsmer won many races. They were brought back to IMSA racing in 1988. The cars were 2,1L 4 cylinder powered, and carried less weight. Toyota's example was to be followed. In 1987, the Ford Mustangs switched from favorites to runner-ups. After the Daytona win, a handful of seconds was the best they could do.
Copyright Kirk Hoffman
One very surprising car was the Dingman Bros Pontiac Fiero, powered by a V6 4,5L. Driven by talented Bob Earl, it went to Victory Lane right from the beginning, on the Miami street course. Designed for slow tracks, it would surely be not so fast on tracks where you need horsepower, but the car had potential. And what about Porsche, you might ask? The cars were outdated, and could not keep up the pace. Chet Vincentz had a strong Porsche 930S, but he could not do better than fifth at West Palm Beach. For 1988, he had opted for a Porsche 944 Turbo and had some strong hopes for the win. The shapes of things to come, we might say. Evolution was the name of the game, definitely.