Development of The Porsche 956

Porsche had been enjoying success with the 935 dominated Group 5 class.  It was around the turn of the 80’s that Porsche America boss Peter Schultz became keen on bringing the firm to Indycar racing and the Indianapolis 500.  A 2.65L twin turbo powerplant was developed for this intent, but a change in CART regulations counted out the move to single seater race cars.  Meanwhile in the sports car division, the plan had been to campaign the street-based 924 Carrera GTR for 1981, but Schultz had greater ambitions than a mere class win for Porsche.  The 936 was wheeled out of the museum, and straight into the workshop where the 2.65L Indycar engine was dropped into the back of it.  Jack Ickx and Derek Bell took the open-topped prototype racer to the top step of the podium at the 1981 24 Hours of Le Mans.  Schultz now needed a new home for his proven noisemaker.  Coinciding with the FIA announcement of Group C rolling out for the 1982 season, it occurred to Porsche that they had the right engine sitting idle at the shop for this upcoming role.  With an initial weight limit for the class set at 800kg and the fuel consumption limit, Porsche knew success in Group C would be a balancing act between the right chassis and engine to deliver both power and efficiency.  Any combination could be the winning formula.  4 cylinders, 12 cylinders – It was an engineer and designers dream.  The manufacturer turned once again to Norbert Singer, the man responsible for extending the life of a tired, 15 year old road car design, and gracing the motorsports world with the ‘Moby Dick’ bodied 935.

Singer, along with his team including Klaus Bischof and Peter Falk were tasked to build a completely new car as the categorical replacement of the successful 936 in compliance with the new technical regulations of Group C racing.  The project started in June of 1981, and a working prototype chassis was rolled out just over 9 months later.  Due to the late delivery of the rules package, many teams were left to guess what the rules would and would not include – BMW had guessed wrong, and pulled the plug on their Group C program.  The 956 was flashed out on paper following the 1981 Le Mans victory.  3 months later and the car had still not even been built.  Another three months after that, it had yet to turn a wheel, but the team worked furiously to deliver a car in time to participate at the second round of the World Championship for Makes.

 Modeller works on the 1:5 scale Type 956 model.  Photograph by Glen Smale

Modeller works on the 1:5 scale Type 956 model.  Photograph by Glen Smale

In August of 1981, Singer and his team constructed a 1:5 scale model for wind tunnel testing.  They looked to exploit a new technology in the world of motorsports aerodynamics known as ground effects.  Only recently being utilized in Formula One vehicles, the objective was to design the body and underbody of the car in a way that created a low pressure zone to essentially ‘suck’ the car into the track surface.  In doing so, the car is planted on the tarmac with a force greater than that which gravity alone can apply.  Downforce was and still is the king of performance factors in all top tier motorsports classes.  Modern Formula One cars, and Le Mans prototype cars often generate enough downforce at high enough speed that the air passing over the body exerts enough downward force alone to hold the vehicle on an upside down surface.  I have a slight feeling however Zurich International may reconsider their policy with Formula One if they tried to confirm said fact.