Porsche’s Journey Through The Group C Era, In Brief

The last day of 2022 – and the first of 2023 will see a blizzard of articles sourced from Porsche on the story behind their iconic 956 and 962 Group C ad IMSA GTP racers as the year of their 40th anniversary expires and the first year of a new era begins.

Here’s the first, an introduction to the overview of the story, before we get stuck into some of the detail of the leaps forward in technology that the programme made, and the successes that followed, coupled with galleries of the cars in action, the people that put them there, and the tech that kept them ahead of the competition – Enjoy – and a very Happy New Year from all at DSC.

The Porsche 956 was designed and built, in record time, as a concept that blended raw speed, cutting edge aerodynamics and fuel efficiency.

The legacy of that car lives on in a number of ways, not least that the challenges of its design and construction meant that Porsche, for the first time in their history, established a major department for motorsport.

Norbert Singer first had a 1:5-scale wooden model built. He recounted the story: “Ferry Porsche took a look at the model and said: ‘I wish you good luck’ and that was it. To him, it was just another racing car. He had presented so many over the years. No one knew at the time what would happen with the car. Could it be successful?”

The team then went into the wind tunnel to create an aerodynamics concept, one that would employ massive downforce to ‘stick’ the car to the ground, known today as the ‘ground effect’. Another novelty for the engineers was the pure aluminium monocoque. “It was mainly a case of ‘learning by doing’,” says Singer, looking back.

“We had no idea how to build monocoques and sought help from the aircraft manufacturer Dornier. We built various boxes and in the end, we actually had a monocoque. By the way: we had started thinking about a carbon monocoque back in 1982. Synthetic materials were just emerging in Formula One. But our team was just too small to develop an aluminium monocoque and a carbon monocoque at the same time.”

Derek Bell, too, recalls the sense of promise at the time: “I had previously driven a Porsche 936 with Jacky Ickx, and we had won Le Mans in 1981. Afterwards, I was invited to the factory by Head of Development Helmuth Bott to talk about the future. Bott said: ‘Next year we’re starting in Group C.’ I had no idea what it was. He said: ‘The car will have a monocoque chassis. We’ve never done anything like this before.’ And added: ‘We’re going to use ground effect. We’ve never done that before either.’ But he also said: ‘We’ve never been wrong.’”

As for the powertrain, Singer opted for the six-cylinder boxer from the Porsche 935/76, an enhanced version of the 911 engine for racing. Thanks to two turbochargers, it was not only more powerful, but also optimised in terms of fuel consumption.

All other vehicle components were newly developed. The racing team was obliged to work under extreme time pressure: the final version of the Group C regulations was not released until October 1981, but the upcoming season was set to start at the beginning of 1982.

Two of the three works cars were only finished two weeks before the race at Le Mans, the third just a few days before.

In January 1982, Bell experienced the new racing car at Le Castellet.

He recalled the day: “It was fantastic, the car was perfect. It was incredibly fast in the corners and was very stable.” Jochen Mass was also among the first drivers; he too remembers being blown away by the 956. “It was so different to all the other racing cars before it,” he said. “It had so much more downforce and was efficient in every detail. With the 956, so many corners just weren’t there anymore. The car was so good that it was now possible to drive them at full throttle. It was also very comfortable to drive, not least on longer runs, because the seats were cushioned and you sat well in them.”

Board Member for Development Helmuth Bott, of all people, was among the few sceptics. He could not imagine that a 620 PS racing car would be faster than its predecessor, the 917, which had 1,000 PS at its disposal. To ensure Singer couldn’t put one past him, Bott personally chose the driver for a comparison, entrusting the task to independent driver Bell. Singer chuckles: “Ultimately the 956 was two seconds faster. Bott was satisfied and even climbed into the racing car himself to get a feel for it.” At Le Mans, however, it was Derek Bell and Jacky Ickx who won the 1982 race in the 956. Jochen Mass and Vern Schuppan took second and Hurley Haywood, Al Holbert and Jürgen Barth came third in their 956. In the end, the racing cars crossed the line in the order of their race numbers: 1, 2 and 3. The Porsche 956 proved its capability in Group C in its very first season back in 1982.

Saving petrol was a key concern from the outset. “For the first time, there was a very clear fuel consumption rule for endurance races,” explains Singer. “You could have a maximum of 100 litres on board and you had to do five pit stops. A maximum of 600 litres were allowed for the entire race distance. But you could never drive the cars down to empty – the danger of getting stuck out there somewhere was too great. It did nevertheless happen on occasion that someone would run out of fuel with two laps to go and would have to wait on the side of the track until they could get filled up there.”

Saving fuel was also a dangerous undertaking, however, as Bell recalls: “We had to tape a piece of paper, about five by seven centimetres, to the centre of the steering wheel. At the top it said: 11, 12, 13. On the side it had the numbers 1 to 13. On the instrument panel there was an indicator or how much fuel we had used at a certain point. So we went out for 11, 12 or 13 laps. If we did 11 laps with the fuel, we were really fast. But that also meant more fuel stops. Every pit stop meant three to four minutes of lost time. We could do 13 laps – very economically, but also very boringly for everyone involved.” The calculating was one thing; but the reading was another thing altogether. “We were doing 360 km/h on the Mulsanne Straight and at the same time we had to look at this little piece of paper and figure out how many laps we’d set out to do. Believe me, we had a tough job in those cars.

German driver Hans-Joachim Stuck joined the Porsche team in 1985: “I drove in a team with Derek. I could rely on him one hundred per cent. We never had an internal rivalry. Sometimes he was faster, sometimes I was. Peter Falk had taught us how we could save extra fuel at Le Mans, for example while braking after the very long Mulsanne Straight. Normally we braked 200 metres before it but were now supposed to ease off the accelerator 400 metres before it and just let the car roll. There were about 10 more corners, so we did it the same way there. This made the distance travelled with the accelerator floored considerably less. What a brilliant idea – that’s how we beat them all.”

The team also had some unusual ideas that helped solve the fuel problem: because the fuel at the respective race tracks was completely inconsistent at the time, the teams never knew how they should tune their engines. Helmut Schmid, an engine man at the time, remembers it well: “We got the notion of using Norbert Singer’s company car, the 944 Turbo. We installed a measuring device and then compared conventional petrol with that at the track. Maximum rpms, full on brakes till everything was glowing. That’s how we got to the knock limit of the engine. And that gave us an advantage because then we knew how to tune the engines in terms of ignition, injection parameters and so on. Later we piggybacked the knock control from the 944 on the steering apparatus in the 962.” Singer sums things up: “A comparison in Spa in 1982 and 1985 shows that the average lap time over the entire race in that period got seven per cent faster while fuel consumption dropped by 23 per cent.”

The Porsche double-clutch transmission, or PDK for short, first used in racing in 1984 in the 956 for testing at Imola, proved a massive relief for the drivers. Stuck was one of the most eager test drivers: “It was a fantastic experience for me to get to know the PDK,” says ‘Striezel’ today. “It proved to be an advantage from the first lap in Weissach, although the lap times were initially a little slower due to the extra weight. You no longer had to let off the gas when upshifting, but could simply keep it floored. And you couldn’t mis-shift any more. At first we had to shift gears with a normal gear stick, which was pushed forward or pulled backward. Soon there were two buttons on the steering wheel – top for upshifting, bottom for downshifting. This meant you could even keep your hands on the wheel in corners. But steering without power steering remained exhausting. At some point there was the idea of installing a steering aid. Bott just said that we boys should train our arms a bit more instead.”

Derek Bell was sceptical about the new PDK technology at first. He had doubts about the reliability of the dual-clutch transmission in endurance racing and the number of stops to install new driveshafts. “But Porsche taught me a lesson: every race is a step in the development. And it worked, because ultimately those in charge had to answer for the technology to their own bosses on Monday morning. The more we used it, the better it got.” For his part, Stuck had no qualms – which had something to do with his time testing the transmission. “I would often drive three or four stints with PDK in Weissach, and then the tank was empty. It would then be filled up and the security people were still there, but the mechanics clocked out. I would empty the tank again, put the car in the garage, close the door and drive home. It was fantastic.”

Jochen Mass first had to get used to the new technology. “The PDK, after all, meant 15 kilograms of extra weight. That 15 kg makes a huge difference when it comes to handling. Because wherever you put it, the car slows down a bit.” The finished PDK, which now no longer required too much power from the engine, with which lap times in testing were now faster than without it and which finally demonstrated its reliability, was installed in the Porsche Group C racing cars in 1986/1987.

An IMSA rule change in 1984 turned the 956 into a 962. Mass explains: “The 962 now simply had more space for the driver’s legs, which ensured that the driver’s limbs were somewhat better protected in case of an accident.” Norbert Singer continues: “In the 962, we moved the front axle 12 cm forward. The layout was the same, only the front overhang was shorter. But it was a bit of work to get the same downforce at the front.”

The lifespan of the 956/962 was so long that subsequent DTM star Bernd Schneider actually drove a 962 in the early 1990s. “The car was an immediate fit with my driving style,” says Schneider today. “But fortunately we had electronic systems for saving fuel by that time. I didn’t have to tape a note to the steering wheel. Sometimes we had up to 900 PS at our disposal. For me, the ground effect in particular was great. I came from Formula One, but at the time the engines weren’t particularly powerful, so there wasn’t much downforce there. When I got into the Porsche, it was incredible. In the fast corners in Spa like the Eau Rouge, we drove full throttle in 1990 with qualifying tyres and in qualifying mode.”

At the end of its triumphant run, the 962 ultimately became a curiosity as the prototype mutated into a GT racer. From 1993, GT cars displaced the sports cars of group C – including at Le Mans. Singer: “Back then Jochen Dauer paid Porsche a visit. He owned several 962 racing cars, but he was no longer able to use them. He asked for help getting a road licence for the 962. At first Porsche declined, but when McLaren offered the F1 with Formula One technology, three seats, a luggage compartment and road approval, they took a 962 and converted it into a road car with a body from Dauer. He was able to compete at Le Mans for just one year, 1994 – and we won the race.”

Production statistics

Type 956

10 works cars

18 customer cars (from 1983) – (plus one car built up by Richard lloyd Racing from spare parts)

Type 962

15 works cars

62 customer cars (excluding cars self-built and rebuilt by customers)

Total production of the 956/962:

28 Porsche 956 (plus one car built up by Richard Lloyd Racing from spare parts)

77 Porsche 962

Including approx. 43 customer vehicles (self-built): approx. 150 total

With thanks to Porsche Motorsport, Porsche Heritage and the Porsche Museum