Porsche’s Group C Icons – 40 Years On: Part 1 – Evolution Of The Rulebook
For the 1982 season, FISA (Fédération Internationale du Sport Automobile) changed the regulations significantly for sports and touring cars. The former groups 1 to 6 were to be reduced to three groups: A (mass-produced touring cars), B (small-series GT vehicles) and C (prototype sports cars). The new regulations for Group C were submitted in draft form in July 1980, with the first official version being published in October 1981. Group C was defined as a pure prototype class. There were therefore no homologation requirements either for the minimum number of vehicles built or the use of series components.
Cars built according to Group C regulations would go on to compete in World Sportscar Championship races held between 1982 and 1992. Group C cars were also to compete in the German Racing Championship (DRM) between 1982 and 1985. This event was set to be held in 1983 and 1984 as the International German Racing Championship and in 1985 as the International German Sportscar Championship. Group C cars were also to compete in the Supercup from 1986 to 1989.
The racing career of Group C cars lasted longest in the North American IMSA GTP series, with vehicles in this class eligible from 1981 to 1993. The 962 IMSA was only entered for the first time in 1984.
The North American IMSA GTP series included both endurance races, such as the 24 Hours of Daytona and the 12 Hours of Sebring, and sprint races on city circuits as well as 200-mile races on permanent racetracks. Group C racing cars were also able eligible for the Interseries.
Fuel consumption formula as a central focus of Group C regulations
From a marketing perspective, vehicle manufacturers saw Group C as a highly attractive proposition, given that most significant sales markets were covered: Europe and Asia had the World Sportscar Championships, while North America had the IMSA GTP series), and the 24 Hours of Le Mans was a race of global renown. As a result, several manufacturers were already getting involved in Group C with factory outfits in the early stages of the formula.
With Group C, FISA replaced both the closed-cockpit production-based racing cars of Group 5 and the open-roofed sports car prototypes of Group 6.
Whereas the former classes were organised according to displacement, Group C took a new direction, with a fuel consumption formula dictating the class. FISA set out a minimum vehicle weight of 800 kg (850 kg from 1984) and a maximum tank capacity of 100 litres. The displacement was exempted, as was the use of forced induction, for example a turbocharger or supercharger.
Five refuelling stops were allowed during a 1,000-km race, which was the minimum distance in the World Sportscar Championship at the time; this equates to a restriction on fuel consumption to 60 litres per 100 km.
This restriction did not, however, apply to the IMSA GTP series, whose races were held outside FISA’s jurisdiction and run according to its own separate regulations. There were no restrictions on fuel consumption for the IMSA series and the fuel tank capacity of an IMSA GTP vehicle was 120 litres. The maximum engine displacement was 2.8 litres. Vehicles also had to be driven by series-produced engines until 1989; this meant that for the IMSA GTP series Porsche had to opt for a fully air-cooled engine based on the 911 (930) Turbo with a single turbocharger.
Since the idea was for as many different manufacturers as possible to get involved in Group C, not just a few financially strong works teams, FISA introduced Group C Junior as far back as 1982, renaming it Group C2 in 1985. The junior category was modelled on the former Group C cars (now known as Group C1), so FISA made use of a fuel consumption formula here too. Racing cars in Group C Junior or Group C2 had a minimum weight of 700 kg and a maximum tank capacity of 55 litres. With five refuelling stops allowed during a 1,000-km race, this worked out at a consumption of 33 litres per 100 km. While Group C1 was dominated by turbocharged racing cars, Group C2 was made up predominantly of cars using naturally aspirated engines.
FISA reduced the amount of fuel permitted by 15 per cent for the 1985 season. This meant a reduction to just 510 litres in a 1,000-km race compared with the previous 600 litres. FISA also adopted some of the regulations used in the US IMSA GTP, such as the roll-over bar (now to be made from steel), and the accelerator, brake and clutch pedals being located behind the front axle. The generational change from the previously dominant 956 to the 962 for IMSA and the 962 C was therefore also evident at Porsche.
Shorter racing distances and engines in line with the Formula One model
The nature of the regulations ensured strong and diverse manufacturer involvement, and the public enjoyed watching exciting races. Yet despite the ever-increasing popularity of Group C in the media and among the public, FISA changed the regulations for the 1989 season. The minimum distance for races in the World Sportscar Championship was initially reduced from 1,000 to 480 km, with a further reduction to 430 being made in 1991.
At the same time, FISA abandoned its fuel consumption formula for the category in 1989. In its place, following the example of Formula One, where turbocharged engines had been banned since 1989, vehicles had to be powered by 3.5-litre naturally aspirated engines. Turbocharged engines with limits placed on fuel consumption were still permitted until the end of 1990. The 1990 regulations therefore included provisions for naturally aspirated engines (category 1) and for turbocharged engines (category 2).
This package of changes meant that the formerly prosperous Group C was seen as increasingly unattractive; the result was that FISA cancelled the 1993 season of the World Sportscar Championship due to a lack of entries. However, GT cars saw a renaissance and starting grids were growing. A final sanctuary for Group C was the 1993 24 Hours of Le Mans. Not many of the Group C vehicles, however, complied with the new regulations concerning 3.5-litre engines. The majority were Group C1 and C2 vehicles, which complied with the old regs.
IMSA GTP
With the entry of further manufacturers, the IMSA GTP series became a major attraction in the second half of the 1980s and attracted numerous top drivers thanks to its high prize money. The racing series was also hugely popular among viewers, since the starting fields were sometimes twice the size of those in Group C.
The series faced a crisis in the 1990s for many reasons. Porsche and other manufacturers withdrew in 1992, and since the Porsche 962 was no longer competitive, more and more private teams also left the series. The following year, audiences and sponsors also ultimately turned away from the racing series, which by then had lost its appeal, and the final race took place in Phoenix on 2 October 1993.
The Porsche 962 C outlives Group C
Although Group C was consigned to the history books in 1994, some Group C vehicles celebrated a remarkable renaissance. In 1994, Jochen Dauer’s team achieved an overall victory at Le Mans with a Dauer 962 Dauer Le Mans GT. This was a Porsche 962 C, which was approved by Dauer for road use and was built for Le Mans according to the regulations of the new GT1 class and therefore competed not as a prototype but as a road-going sports car.
Counterparts to the Dauer 962 Dauer Le Mans GT were the Schuppan 962 CR, which was also road-legal, and the Koenig-Specials C62.
The Porsche 962 C surfaced again, in part at least, in 1996 and 1997. In both these years, Reinhold Joest’s team took first place with a vehicle known as TWR Porsche WSC-95.
This was an open-cockpit racing car, which combined a Jaguar XJR-14 chassis with a Porsche 962 C engine. The Cologne-based Kremer team also developed three vehicles based on the Porsche 962, which entered races between 1994 and 1998 under the name Kremer K8 Spyder.
With thanks to the teams at Porsche Motorsport, Porsche Heritage and the Porsche Museum
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