Porsche sports car development: Le Mans winning cars
With a total of eighteen overall wins at Le Mans, Porsche holds the unbeaten record for the 24-hour race – and its victories have been won with a wide range of different racing cars, each of which was at the technological cutting edge of its era.
After racking up multiple class victories and many race starts, Porsche first achieved its long-held ambition of being crowned the overall winner at Le Mans in 1970, with the 917 K (for ‘Kurzheck’ or short tail) Coupé. When the new regulations for the sports car world championship were published at the end of 1967, Porsche decided to design a car for the up to five-litre engine displacement class. At that time, the vehicle was still required to enter small-scale series production for homologation purposes. The 917 was equipped with an air-cooled twelve-cylinder engine; the 4.9-litre version delivered 580 hp (426 kW) at 8,300 rpm. Hans Herrmann (DE) and Richard Attwood (GB) won the 1970 race in the red 917 from Porsche Salzburg. “The circumstances were a little strange,” recalls Attwood. Before the race, he voiced two conservative wishes: “Firstly, I wanted the 4.5-litre twelve-cylinder engine instead of the five-litre engine, which I considered too fragile. Secondly, I wanted the short rear end version of the 917, because the long rear end felt unstable.” After qualifying, the dejected pair found themselves in fifteenth place, regretting their decision for the safer option. But in the race itself, consistency and reliability won out.
1971 saw a further victory for a 917 Kurzheck – this time with Gijs van Lennep (NL) and Helmut Marko (AT) at the wheel. The pair only found out afterwards that the car was fitted with an ultra-light – but highly controversial – magnesium tube frame. The 800-kilogram 4.9-litre sports car also featured some unusual adjustments for aerodynamics: The “shark fins” on the rear were designed to improve stability and reduce drag by eleven per cent. On their journey to the second Porsche win, van Lennep and Marko broke two records, which would stand for another 39 years – covering a distance of 5,335.16 km (3,315 miles) and achieving an average speed of 222.3 km/h (138 mph). They also won the “Index of Performance” for the lowest fuel consumption in their engine category.
In terms of displacement, the next Porsche winner – the first successful turbo at the Circuit de la Sarthe – was dwarfed by its predecessor. In 1976, the race was won by the 936 Spyder, fitted with a 2.1-litre six-cylinder flat biturbo from the 911 Turbo RSR, delivering 540 hp (397 kW). Aluminium was now available as a light and – compared to magnesium – safe material for the tube frame of the open car. The aerodynamically optimised body was made of plastic; van Lennep and Jacky Ickx (BE) took turns to drive. Ickx achieved his greatest Le Mans victory with the 936 Spyder the following year: In 1977, after his own 936 broke down, he joined Jürgen Barth (DE) and Hurley Haywood (USA), who had encountered problems of their own and were lagging behind in 42nd place. “What happened next was exhilarating”, says Ickx, even today, so many years after the event. “I drove all night, getting faster and faster, despite the rain and the fog. We got to position 35, 28, 20, nine, six, five – everyone sensed that we might just achieve what had previously been unimaginable. Jürgen and Hurley drove faster than ever, and the mechanics were unbelievable.” In the morning, three Renaults retired from the race – leaving the 936 16 laps ahead. In the last hour, one of the cylinders in the six-cylinder Porsche engine failed. But Barth managed to bring the damaged 936 home to victory.
In 1979, the works team’s 936s were favourites to win, but encountered some obstacles along the way. The fifth overall win for Porsche came in the form of private team Kremer Racing in a 935K3 – a racing version of the 911 with a three-litre, six-cylinder flat engine. This 600-hp (441 kW) variant represented the start of an age in which series-produced racing cars dominated the so-called Group 5 category. Visually, the car had very little in common with the 911 Turbo. The 935 was bulkier, with a flat front and an imposing twin wing on the rear. This 935 was the first car with a water-cooled four-valve cylinder head, which was later put into series production.
By 1981, the old Group 6 prototypes had been readmitted to the race at Le Mans. By this time, the 936 had a larger turbo engine with 2.6-litre displacement; Ickx and Derek Bell (GB) won with a 186-kilometre (115.1-mile) lead.
In 1982, the same drivers achieved the seventh overall race victory for Porsche, this time in a completely new vehicle: The era of group C was under way, and the innovative and uncompromising Porsche 956 had an unbeaten run for many years of the Le Mans race (winning in 1982, 1983, 1984 and 1985). The car – the first Porsche racing car with an aluminium monocoque chassis and ground effect aerodynamics – benefited from a highly efficient six-cylinder flat biturbo. The next incarnation of this futuristic car was the Porsche 962 C, which the works team drove to victory in 1986 and 1987. The group C racers, the 956 and 962, were also the launching pad for a new technical revolution: the Porsche double-clutch transmission. For the first time ever, the Porsche Doppelkupplung (PDK) allowed drivers to change gear without interrupting traction.
When group C came to an end, it was replaced by new prototype classes for which Porsche never developed a works car. But its victories at Le Mans continued to rise: In 1994, a modified Dauer 962 won the new GT1 class. In 1996 and 1997, Joest Racing emerged victorious in the TWR Porsche.
The 911 GT1, developed by Porsche for works and customer use in GT motorsport, made its racing début at Le Mans in 1996. The GT1 class was for closed sports cars based on series-production cars. They could compete with the Class 1 prototypes, some of which were open cockpit in design, for first place on the podium.
The GT1 was the first 911 ever to be fitted with a water-cooled mid-engine, which was combined with a balanced axle weight distribution and aerodynamic improvements. In 1998, Porsche used a carbon-fibre chassis for the first time in the reworked GT1. As a result of its carbon-fibre-reinforced plastic monocoque, a redesigned front suspension and a reduced-weight battery and generator, the GT1 was around 50 kilograms lighter for the 1998 race. The three-plate carbon-fibre race clutch was also new. The six-cylinder flat biturbo engine – carefully tuned to optimise consumption – was by now capable of delivering 550 hp (405 kW).
In 1998, the year of its 50th anniversary, Porsche had yet more reasons to celebrate when two GT1s placed first and second in the race. The winning driver team was comprised of Laurent Aïello (FR), Allan McNish (GB) and Stéphane Ortelli (MC). Porsche fans had many years to savour this success; the company did not enter a works racing car in the top category again until 2014. Though in the hands of the customer motorsport teams, the 911 RSR was a familiar class winner in the GT category throughout. With the futuristic Porsche 919 Hybrid, Porsche raced to its 17th and 18th overall victories in Le Mans in 2015 and 2016.