Porsche 956 (1982-1983), 956 B (1984)
Premiere: May 15, 1982 Silverstone
Le Mans winner 1982-1983-1984-1985
|Engine||2.6 F6 twin-turbo, approx. 455-470 kW @8200 rpm, 4 valves per cylinder, water-cooled cylinder heads, air-cooled cylinders|
|Weight||820-855 kg / 1800-1900 lb|
|Fuel tank||99 L (allowed size 100 L)|
|Dimensions||length 4800 mm, wheelbase 2650 mm (allowed length tied to wheelbase), width 2000 mm (allowed maximum)|
|Top speed||350+ kph / 218+ mph|
|Production||25 (28 numbered chassis built, but some used to rebuild earlier crash cars)|
FIA had announced new racing classes in time for the 1982 season. Group A was meant for cars that were built from 4-seater mass-produced cars (production capacity at least 5000 units a year). Group B was for heavily modified cars and saw some of the greatest rally cars ever created. Group C was the new class for the prototype sports cars. Group C cars were allowed a minimum weight of 800 kg and a race average fuel consumption of up to 60 L/100 km. Because of the fuel consumption limit and reliability issues the power of the cars was in the region of 600 hp.
With the rules on his desk in Porsche's research and development center in Weissach, racing engineer Norbert Singer put his team to work in June 1981 to create the first Porsche with ground-effect aerodynamics.
The regulations stipulate the proportion of overall length to the wheelbase, to avoid excessive long tail constructions. Porsche decides on a wheelbase measuring 265 cm (+35 cm compared to the 917). In August 1981 Singer's team works with the first 1:5 model in the wind tunnel. As a new advantage they were to exploit the ground-effect known from Formula 1 cars. The shape of the underbody and the sidepods generate an under pressure which sucks the car to the track surface. The 956 is also the first Porsche to feature an aluminium monocoque chassis which is 80% stiffer than was the frame of the 936. As the power was restricted by the fuel consumption, there was no need for the new engine. The 2.65-litre twin-turbo seen in the 1981 Le Mans-winning 936 would work well. Everything else on the vehicle was new, including the gearbox.
On March 27, 1982, Jürgen Barth, the leader of Porsche racing department, takes the revolutionary 956 (chassis 001) to the Weissach test track for the first time. Although F1-type lateral skirts that prevented air from flowing in from the sides were not allowed for Group C vehicles, the 956 realised cornering speeds previously thought impossible for racing sports cars.
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Article © James Herne / Stuttcars.com
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