How the Porsche 956 cracked the Group C formula: Right first time

“Those rules were brilliant,” sighs Jonathan Palmer, one of the very quickest Group C Porsche drivers. “A fuel consumption formula that was 20 years ahead of the global economy. What made Group C was that it was an engineer’s formula. You had four, six, eight and twelve cylinder cars, normal aspiration and turbocharging. There were so many different sights and sounds and, in that most creative environment, you’d always back Porsche to do its maths properly.”

Quite so. But even by Porsche standards the 956 was a mammoth undertaking, for it was anything other than just the next in a long line of racing cars.

In two critical respects the 956 would break new ground for Porsche. First, and somewhat staggeringly, Porsche had never built a monocoque racing car before, despite the known strength, stiffness and light weight of a structure that combined body and chassis into a single load-bearing form rather than carrying a separate skeleton like a spaceframe or ladder chassis. The technology was hardly new: in the world of sports cars the Jaguar D-type had a semi-monocoque construction in 1954, the Lola T70 a full monocoque in 1965. But Porsche had stayed faithful to spaceframes all through the 908 and 917 eras and then right up to and including the 936. Since the 936 had proven good enough to win Le Mans in 1981 when it was already a five-year-old design, you could perhaps see why. Indeed Porsche only decided to make the 956 a monocoque car when it couldn’t get the crash protection mandated by the FIA with a space-frame.

The second departure for Porsche was prompted by the fact that the 956 would be its first racer to be developed after the discovery of ground effect. The challenge was not simply to understand the physics but also to adapt a sports car design to make the most of it, without the use of the skirts that sealed the undersides of Formula 1 cars. The pitch to two-time Le Mans winner Derek Bell from Dr Helmuth Bott was simple: “He said ‘Derek, we have never done a monocoque car before. We have never done a ground effect car before. But Derek, we have never been wrong before.’” Bell duly signed and was the only man to race Group C cars for the factory from first to last. He would also add three more Le Mans wins in between, too.

Yet still some habits died hard. Porsche would have been entirely within the rules to produce a brand new engine for the 956 and there was a compelling reason why they should. Just as Ferrari had been denied access to the F1 ground effect bandwagon by their flat-formation twelve-cylinder engine, so too did Porsche’s traditional flat-six motor get in the way of the tunnels and venturi so vital to controlling the air flow under the car. A vee-formation engine would have been perfect but Porsche lacked the time and almost certainly the money to develop such a motor for the 956. So instead it took the 2.65-litre flat-six twin-turbo engine from the 936 unchanged, except where it needed to be externally modified to it.

And true to traditional Porsche form, a racing dog box was eschewed in favour of a fully synchronised five-speed transmission. Tiff Needell: “The whole car was a bit of a culture shock to those of us coming from single-seaters, and that slow, ponderous syncromesh gearbox in particular. But it got the job done.”

Less easily appreciated today is how quickly Porsche designed, built and developed the 956. Last year it announced its return to Le Mans in 2014 and even in the unlikely event that it had not at that stage done any design work, that still gives the factory three clear years to build their challenger. By contrast, one year before the 1982 Le Mans the 956 had not even been approved. Indeed, six months before Le Mans, the first car, the Rothmans car you see here, had not even been built; and three months before Le Mans it had not even run. It first moved under its own power at Weissach on March 22, just 89 days before the flag fell at Le Mans. In the event, so good was the car’s fundamental design that 956/001 actually made its race debut on May 16 and ran trouble-free at Silverstone for six hours straight.

So what was this extraordinary device like to drive? Was it like stepping into another world? Apparently not. “At first it didn’t seem that different,” concedes Bell. “You had to really drive it hard and get the ground effect working properly before you realised it was, in fact, unlike any other sports car.”

Ickx agrees: “I can remember testing it at Paul Ricard. Back then there was a corner which was nowhere near flat in the 936 and it didn’t seem to be in the 956. But then you built up to it and realised that maybe it was. And then once you’d gone through lat that was that, you were lat every lap.”

The perspective of John Watson is also worth having. He is one of two people (Price Cobb being the other) who raced both for the Porsche factory team and its nemesis, TWR Jaguar. “Both cars were limited by their engines – the Porsche because its flat six was not good for ground effect, the Jaguar because its V12 was huge, heavy and based on a road car engine. But the Porsche was such a good Le Mans car that despite the limitations of its aluminium tub [the Jaguar had a carbon fibre monocoque] there was precious little between them. Of course it helped that at Le Mans you always ran the car in low drag, low downforce configuration…”

But most of all when you talk to drivers about the 956 and 962 there is a quorum of opinion that says their success was not just because the car was so quick, but also that it was so easy to drive. “It was physically hard work,” says Palmer, “with its unassisted steering and steel brakes, but it was also a very forgiving car and I think that’s one reason the customer programme did so well. Gentlemen drivers could climb aboard and really hustle it, knowing it would look after you. And it was properly quick too.”

Bell feels the same way: “Apart from the understeer caused by the spool diff effectively locking the back axle, it was absolutely viceless. Porsche understood better than anyone that it was not enough for the car just to be fast: it had to be fast for 24 hours, regardless of the talent of the bloke behind the wheel or how tired he was. Which meant it had to be easy to drive.”

There are some dissenting voices, however. While Tiff grew to love it for its durability and the success it brought, to drive he describes it as “truck-like, a bit of a brute force and ignorance machine”, while Klaus Ludwig was simply scared by the thing, particularly at the pre-chicane Le Mans where its low-drag body would let it wander somewhat imprecisely down to Mulsanne at over 240mph. “I can remember being quite jealous of the Jaguar drivers in their carbon-ibre monocoques.”

But their lack of space-age materials did not stop first the 956 and then the 962 sweeping all before them. At Le Mans in 1982 three factory 956s started the race and three factory 956s filled the podium; thereafter it would be 1987 before anything other than a 956 or 962 did better than sixth.

Of course the factory could not have done this alone, and the tale of the privateer 956s and 962s would merit a story of its own. Teams like Brun Motorsport, Joest, Kremer, Richard Lloyd Racing and John Fitzpatrick Racing were always there to plug the gaps if the factory faltered or if, on occasions like Le Mans in 1984, the works objected to last-minute rule changes and refused to come. And while the factory kept the very latest updates to themselves for a while, a customer car would always be competitive, and with the right drivers and strategy still capable of beating the works. Indeed, the first time the customer cars went up against the factory at the opening round of the 1983 championship, the Joest 956 of Bob Wollek and Thierry Boutsen came home ahead of the Ickx/Mass Porsche car.

I remember the late Richard Lloyd telling me about Porsche customer care: “There’d be no fanfare, no ritual handing over of the keys in some glossy showroom. You’d just be shown round the back where the car would be parked and that was that. I expect they’d have made more of a fuss of you if you were collecting a 924. But you’d load up the car, take it testing and without changing a thing, it would be competitive on its first lap out of the lorry. That probably mattered more…”

What makes the 956 and 962’s achievement all the more impressive is that it was done with remarkably little modification to the original concept. “Porsche was always tinkering,” remembers Derek, “but save the rule change that made them extend the wheelbase and turn the 956 into the 962, the basic design stayed the same.”

But faster the car became: to claim pole at Le Mans in 1988, the Shell Dunlop car you see here circulated the track some 13sec faster than 956/002 had managed in 1982. The biggest advance had been found in the engine department where power outputs had risen from around 650bhp for an early 956 to perhaps as much as 850bhp for the last works 962 running qualifying boost, partly thanks to an increase in capacity from 2.65 to 3-litres.

Just as important was that the car was able to produce more power while using less fuel, which gained even greater significance when fuel tank capacity was reduced for the 1985 season. What made it possible was the adoption by the factory in 1983 of Bosch Motronic engine management able to administer both the fuel injection and electronic ignition. This in turn allowed Porsche to raise the compression ratio of the engine from not much more than 7.0:1 in 1982 to eventually up to 9.0:1 which not only significantly reduced turbo lag, it also brought huge improvements in fuel consumption. Motronic would not be made available to customers until 1985, with cars so equipped coming to be known as the Porsche 956B.

Meanwhile Porsche’s only miscalculation was that the 956 received the cold shoulder from the IMSA authorities. Their rules forbade the use of twin turbos and their regulators objected to the fact that the 956 placed the feet of the driver ahead of the front axle line. So it was to become compliant with IMSA’s demands and thereby gain access to the North American racing scene that the 962 was built. Its wheelbase was extended by a massive 4.8 inches, and its engine was fitted with a single, huge KKK turbo replacing the two smaller units used elsewhere in the world. The 962 made its debut in America in 1984, and using engines of 2.85 and 3.2-litre capacities, it would go on to dominate racing there from 1985 to 1987.

The success of the 956 and 962 can be measured in many ways, but perhaps none more convincing than the sheer total built. Even after the factory stopped racing, it continued to support private teams. According to Karl Ludvigsen, by 1991 a staggering 148 chassis had been built, the vast majority of them 962s. Interestingly only 105 of them were made by Porsche itself; many privateers took it upon themselves to address the perceived lack of structural strength of the single-skin monocoque by creating their own tubs.

The result is that the 962 stayed competitive long after all common sense said it should have become obsolete. At qualifying at Le Mans in 1990, Brun’s 962 was beaten only by Mark Blundell’s jammed-wastegate hero lap in the Nissan R90CK. In the race itself Jesús Pareja retired from a podium position with a mere 15 minutes of racing left on the clock. Into the void stepped another, the Alpha Racing 962C driven by Tiff, David Sears and Anthony Reid. Not counting the 1994 Dauer anomaly, “it was the last ever Le Mans podium for the 962,” remembers Tiff today, “our little team beaten only by two works Jaguars.”

And then Group C turned to normally aspirated 3.5-litre cars for 1992 and, Dauer adventure aside, the day of the 962 was done. It will be interesting, therefore, to see what Porsche produces in 2014 and whether it will be happy to sell and support customer cars. At the time I can remember becoming quite bored by the relentless Porsche domination of Group C, but now I feel the same way about the 12-year-old Audi steamroller. A new 956/962 to give Ingolstadt something to think about cannot come a moment too soon.

With great thanks to Henry Pearman and the Historic Porsche Collection for making this feature possible