Porsche 956/962

At the top for a decade

Created specifically for the new Group C that was launched in 1982, the Porsche 956 and the 962 would build an impressive track record leaving little room for the competition.

As has often happened, the engineers at the Porsche Research and Development Centre in Weissach took the opportunity to innovate the design of their latest racing machine. For the first time, the traditional tubular chassis was replaced by an aluminium shell. In addition, they opted for a body with an aerodynamic design that boosted the "Ground Effect", a technique widely used at the time.

The Rothmans Porsche 962 C driven by Derek Bell, Al Holbert and Hans Stuck won the 1986 Le Mans 24 Hours with an average speed of 207.197 km/h. © IXO Collections SAS - Tous droits réservés. Crédits photo © Porsche / D.R.

In the late 1970s, many of the constructors involved in endurance racing gradually lost interest in the World Sports Car Championship. This was especially the case after Renault-Alpine withdrew from the competition following its 1978 victory, and that ended the exciting technical rivalry between Porsche and Renault. This rivalry had until then created a race between the teams, with endurance racing and especially the 24 Hours of Le Mans taking centre stage. In order to revive the championship, the Fédération Internationale du Sport Automobile decided to revise the regulations of this discipline with the creation of the new Group C in 1982.

Of the private teams that raced 956s, Joest Racing was one of the most successful. In 1986, the team of George Follmer, John Morton and Kemper Miller finished third at Le Mans. © IXO Collections SAS - Tous droits réservés. Crédits photo © Porsche / D.R.

Weissach's ultimate weapon

Months before the publication of the new Group C regulations, the engineers in Weissach were already working on the creation of the future 956. Norbert Singer, the project manager of the 956, was given a free hand by Peter Falk, who was in charge of the development of the racing cars and also was Porsche's racing director. Engineer Horst Reitter was commissioned to design a chassis with riveted aluminium panels which proved to be much more rigid than a tubular frame. In November 1981, the first aerodynamic tests were carried out in the wind tunnel of the University of Stuttgart. In March 1982, the bodywork design was completed and the technical set-up was I initiated.

The preferred solution was to place the turbos and exhausts sideways so as not to disturb the internal airflow at the rear. It was then up to in-house test driver Jürgen Barth to carry out the necessary tests at the Weissach circuit and then at Le Castellet. The following month, the Porsche 956 was now ready to begin its phenomenal career. A total of 121 956/962 chassis were built, of which 28 examples of the 956 in the 1982-1984 period (10 of which were for the factory) and 93 examples of the 962 in the 1984-1991 period (16 of which were for the factory).

The Porsche Research and Development Centre in Weissach was able to take less than a year to take the car from the drawing board to its first victory. This is the spare chassis of 1986. © IXO Collections SAS - Tous droits réservés. Crédits photo © Porsche / D.R.

Chassis with a ground effect

The engine in the 956 was not unfamiliar, as it had previously been used in the 936/81 that won the 1981 24 Hours of Le Mans. The flat six cylinders of the 935-76 block type were air-cooled by a central turbine, while the cylinder heads were water-cooled.

The engine equipped with a Bosch Kugelfischer mechanical fuel injection system, was replaced by a Bosch Motronic system in 1983. The powertrain had no load-bearing capacity: it was placed in a tubular frame fixed in line with the hull, in a position inclined towards the front in order to clear the pontoons and to favour the ground effect. The gearbox was fully enclosed and the combined shock springs (Bilstein) were placed above it using rocker arms. The "ground effect" was cleverly applied to the Porsche-developed 956. The bodywork, the underbody extended by a diffuser and the large rear wing were analyzed in a wind tunnel to create a low pressure zone that literally glued it to the track. In January 1984, the Porsche 962 was launched and in 1985 the 962 C), looking very similar to the 956, and both versions would cohabit for several seasons. The cubic capacity of the 956 and the 962 evolved according to Endurance Championship regulations, reaching successively 2,677 cm3 in 1986, 2,996 cm3 in 1987 and 3,640 cm3 from 1988 onwards.

In 1990, the Porsche 962 was still a strong contender in endurance racing. The team Yver, Lässig and Altenbach (Écurie Obermaier Primagaz) finished 9th at Le Mans. © IXO Collections SAS - Tous droits réservés. Crédits photo © Porsche / D.R.

A masterful dominance

Barely three weeks after a final closed test session at the Paul Ricard circuit in Le Castellet, the Porsche 956 made its debut at the second round of the 6 Hours of Silverstone on 16 May 1982. Immediately, the car was successful and the team of Derek Bell and Jacky Ickx finished second behind the Lancia LC1 of Patrese and Alboreto. A month later, at the 24 Hours of Le Mans, the three participating Porsche 956s of the Rothmans Porsche Team took the first three positions, with Ickx and Bell as winners. Until 1987, the 956/962 achieved six consecutive victories at Le Mans, while Porsche won the Constructors' Championship from 1982 to 1986 and Jacky Ickx, Derek Bell, Hans Stuck and Stefan Bellof won the Drivers' Titles during the same period.

Technical data

Porsche 956 (Le Mans 24 Hours 1983)

• Engine: type 935/76, 6 cylinders, flat opposed, longitudinal centre rear

• Displacement: 2,649 cm3

• Bore x stroke: 92.3 mm x 66 mm

• Power: 620 hp at 6,500 rpm

• Fuel: Bosch Motronic injection, 2 KKK turbos

• Ignition: Bosch electronic management

• Timing: Dual overhead camshafts per bank, 4 valves per cylinder

• Transmission: Getrag G31, rear wheel drive, 5-speed manual + M.A.

• Tyres: Dunlop-Denloc, 280/600 x 16 (front) and 350/650 x 16 (rear)

• Brakes: ventilated discs (front and rear), twin calipers

• Length: 480 cm

• Width: 200 cm

• Height: 103 cm

• Wheelbase: 265 cm

• Front track: 166.5 cm

• Rear track: 154.5 cm

• Weight (empty): 840 kg

• Maximum speed: 370 km/h

The new Group C

The Group C regulations were presented in October 1981 and went into effect the following season. Paul Frère, former driver and member of the FISA technical committee, described the regulations at the time as "fair and intended to give manufacturers a lot of freedom". The intention was to rearrange Group 5 (Silhouettes) and Group 6 (Prototypes), which were allowed to remain within Group C until the end of 1982. This new category was opened to two-seaters with enclosed bodies weighing more than 800 kg. All engines were to come from manufacturers that already had obtained Group A or B homologation. FISA's idea was to limit the power of Group C engines not by engine capacity, currently free, but by consumption. Thus, fuel tanks should not exceed 100 litres, while the number of fuel stops during the race was limited to five for 1,000km events and 25 for 24-hour events.