Audi 90 quattro IMSA GTO - foto

[ChriS3]

The new racer used a tube frame design, which allowed for a revised suspension that incorporated double wishbone arms and coil-over shock absorbers. This construction also allowed the engine to be moved further back towards the center of the car for better weight distribution. Of course, the most interesting features of Audi Quattro's is the all-wheel-drive system. The central differential was a self-locking TORSEN. The front differential was a limited-slip setup with a viscous coupling whereas the rear used a multi-plate coupling. Audi described the arrangement used on the IMSA cars as an extremely advanced version of the current production system. This feature caused the greatest amount of concern amongst competitors. As the all-wheel-drive system would provide a distinct advantage in adverse conditions.
The connection between the all-wheel-drive system and engine was made using an all-synchromesh 6-speed transmission. One of the gears was disabled as IMSA rules limited the number of forward gears to five. The driveline also incorporated a twin plate clutch.
Another unique design feature of Audi's is their engines. The car was equipped with a five-cylinder 2.2 litre turbocharged engine that had 4-valves per cylinder. The electronics for the engine was controlled by a Bosch Motronic MP 1.7 system. A dry sump system, which held 12.6 quarts of oil, was used to lubricate the engine. These features and the IMSA engine rules allowed Audi to generate an additional 110 horsepower (from 510 hp to 620 hp) over the Trans Am prepared motors.
The cars were equipped with four-piston calipers and ventilated rotors, which featured carbon fiber brake pads for extended life and better stopping. Fourteen-inch diameter alloy wheels - 17 inches wide were fitted with Goodyear racing tires.

A year later the company switched to the IMSA GTO series, with its less strict rules. Only the silhouette of the Audi 90 quattro was retained: under the GTO’s carbon-fibre skin was a pure racing car. The five-cylinder engine, in its final development stage, produced 529 kW (720 bhp), and the car’s four driven wheels had 14-inch wide rims. With seven wins in 13 races, Hans Joachim Stuck took third place in the championship and the team came second in the manufacturers’ rankings.






[ame]http://www.youtube.com/watch?v=5RkCx9yln4g&feature=player_embedded[/ame]
[ame]http://www.youtube.com/watch?v=-Q5meb2yB0w[/ame]