Group C – Porsche
Regarded by many as a modern ‘golden age’ of sports car racing, the FIA’s new Group C category for prototypes lasted from 1982 to 1993. It was designed to replace both Group 5 (closed touring prototypes like the 935) and Group 6 (open sports car prototypes like the 936). As interest in Group C grew, the world’s major motor manufacturers joined the fray with Porsche, Jaguar, Ford, Aston Martin, Lancia, Mercedes-Benz, Mazda, Nissan and Toyota, eventually all fielding works entries and attracting major sponsorship from big brand companies whose liveries became famous on these highly effective and attractive racing cars.
Rather than being based predominantly on engine capacity and weight, the traditional parameters of motor racing formulae, Group C placed a limit on the amount of fuel permitted but otherwise allowed constructors virtually a free hand in design. Porsche responded immediately to the challenge and in just nine months, Norbert Singer oversaw an engineering team at the Porsche motorsport department in Weissach, to design, construct and develop the new Porsche 956.
Aerodynamic development started in mid August 1981 in the Stuttgart University wind tunnel, where Norbert Singer experimented with 1/5 scale models during development of the 956 concept.
The 956 was the first Porsche ever to utilize an aluminium, monocoque chassis, which not only increased rigidity over the traditional tubular space-frame construction but combined with state-of-the-art chassis and underbody tunnels, a closed-cockpit bodywork design was developed to create a ground-effect racing car able to produce significant down force at high speeds.
Power for the 956 was derived from a version of the tried-and-tested Porsche twin-turbocharged flat-six engine, which had previously powered the 1981 Le Mans-winning Porsche 936. Designated the Type 935/76, it had water-cooled cylinder heads and air-cooled cylinders. Air fed into a Naca duct in the roof, which channeled down to the engine and then emerged from under the car through openings in the lower bodywork, which slightly upset the ground-effect. The exhaust exits were located on either side of the bodywork, just in front or the rear wheels so as not to upset the air flow any further. The 2,650cc KKK-turbocharged unit was estimated to develop 630bhp at 8,200rpm and have a top speed of circa 240mph. Because of Porsche’s immediate success with the works Rothmans Porsche 956s, a further 11 examples were supplied directly to ‘customer teams’ to also race in the FIA World Endurance Championship. Porschesport customer racing services AvD sold the 956 as turn-key racing car which were fully-supported by the factory, who undertook engine preparation, also supplying a comprehensive 956 parts catalogue along with a large parts-service truck at each Group C race, which could provide everything needed for running a 956 chassis.
The 956B development
Released for the 1984 season, the 956B was the ultimate development of the 956 – built to the 1983 works Rothmans specification, with modified suspension and a one-piece under-body, but now running Bosh Motronic fuel injection. The Motronic fully electronic and integrated ignition and injection system made much closer control of the combustion process possible, providing more power, better fuel consumption and a more progressive throttle response. Combined with Norbert Singer’s further aero development to the underbody, the 956B became the ultimate specification of the 956.
Just four 956Bs were originally built for World Sportscar Championship customer teams – three of these cars survive:
956-114 John Fitzpatrick / SKOAL Bandit (3rd, 4thand 4that Le Mans in 84, 85, 86)
956-115 Kremer Porsche Racing / LIQUI MOLY (Norisring Winner)
956-116 Brun Motorsport / Schiesser – (Destroyed at Spa 1985 / Bellof)
956-117 Joest Porsche / NEWMAN (Double Le Mans Winner 1984 & 1985)
Racing history: 956-114
27 races, 1 win, 2 second places, 3 third places, 4 fourth places, 1 fifth place
John Fitzpatrick Racing took delivery of 956-114 from Porsche on 16th April 1984. A week later the car was debuted at Monza 1000 kms with Hobbs and Boutsen at the wheel. The car then taken to the Silverstone 1000 kms in May during the run up to the 1984 Le Mans 24 Hours.
At Le Sarthe David Hobbs teamed up with Philpe Streif and Sarel van der Merwe, winner of the 1984 Daytona 24 Hours. The team’s main difficulty in practise was an engine problem due to a wrongly installed camshaft. Despite the time lost, Hobbs qualified the car in sixth place. At 4pm 956-114 made a cautious start to the race but by nightfall ‘Hobbo’ was out in front, having taken the lead when the fastest Lancia had a suspension breakage. The lead changed several times between the Bandit and the Joest Newman Porsches. At 6.30am 956-114 developed a misfire, which neither black box nor spark plugs could rectify, eventually the problem was diagnosed to a burnt valve and one cylinder was isolated. For the next 10 hours 956-114 was driven flat out on five cylinders in the intense heat of 1984 and pressed on to a well earned third place, behind the Porsche 956 of Preston Henn, Jean Rondeau and John Paul Jr and the winning Joest Newman Porsche 956B of Henri Pescarlo and Klaus Ludwig.
956-114 again returned to Le Mans in 1985 with John Fitzpatrick Racing but in new livery sponsorship from American100s, finishing 4th overall. The final assault in 1986 saw JFR run the same car in Danone livery, once again finishing 4thoverall.
Ultimate John Fitzpatrick Group C Porsches / The Definitive History – Mark Cole
Porsche 956 – Reynald Hézard & David Legangneux