1978 Porsche 935/78 - Images, Specifications and Information

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In the quest to take an overall win at Le Mans, Porsche had moved far away from the principal that the company's racing cars should at least be related to the road cars. So after the 1970 and 1971 editions were won by the 917, it was no surprise that Porsche returned to their roots with a range of 911 based racers. The first of these were the Carrera RSR models based on the naturally aspirated 911. From the 1976 season these were replaced by a Group 4 and Group 5 racer derived from the recently introduced 911 Turbo or '930'. Especially the Group 5 car, dubbed the 935, had the priority of the Works team as that year's World Championship would be run for this type of racer.

Both the road going 930 and its racing derivatives found their roots in the experimental RSR based Turbos that were extensively raced in the three litre prototype class in the previous years. Taking in account the 1.4 turbo equivalency factor, it used a 2.1 litre six cylinder engine, which would be enlarged to three litres for the road car. The 934 Group 4 car was very similar to the street spec 911 Turbo and only raced by privateers and was nevertheless very successful in its class. The Group 5 homologation allowed for many more modifications with a minimum weight based on displacement as its most important rule.

In order to fit in the 'under the four litre' and '970 kg' group, the 935's engine could displace no more than 2857 cc. By using a slightly smaller bore of 92 mm, a displacement of just over 2.8 litre engine was created. A very large KKK turbocharger was hung behind the engine, mated to an intercooler. In this specification the turbocharged engine was good for 590 - 630 bhp depending on tune. The four speed gearbox was derived similar to that fitted to the Turbo road car and it was an altogether more sturdy 'box than the one that had proven to be the RSR Turbo's weak spot.

What really set Group 4 and Group 5 apart was the amount of work allowed on the chassis and body. The suspension was uprated with coil springs instead of torsion bars, adjustable anti-roll bars, and vented and cross-drilled discs were fitted all around. Outwardly the first incarnation of the 935 was very similar to the RSR Turbo with the basic 911 nose, extremely flared wheel-arches and a massive rear wing. After extensive testing, the original nose with the headlights poking out was found to create drag. It was controversially replaced by a flat nose with the lights moved into the bumpers.

Two cars were ready in time for the season opening races at Mugello and Vallelunga and with back to back wins the 935 looked set to become an instant success. It all changed dramatically when the sport's governing body asked whether the original 930 engine cover would still fit as required by the rules. The big intercooler prevented this and until a solution was found, the 935 was not allowed to race. A quick fix was the installation of the intercoolers fitted on the 934, but it took several races before that setup was made reliable. In the mean time BMW had been reeling in victories, but fortunately for Porsche, the revised 935s were ready in time to claim enough points to clinch the World Championship.

While assembling the first customer 935s late in 1976, Porsche was already busy developing the Works car for 1977 to defend the title. There were many detail changes to the running gear, suspension and aerodynamics, but what really set the 935/77 apart from its predecessor was the engine. Replacing the single large turbocharger were two smaller KKK units. These were used in the hopes of reducing turbo lag and also saw performance increase to 630 bhp and 680 bhp at the end of the season. With the bugs fully ironed there was very little the competition could do and the two-car Works team reigned supreme. One 935 was fielded at Le Mans, but was forced to retire fairly early on with a blown engine.

Following the previous year's pattern, Porsche produced customer racing cars following the proven specification, while working on a new development for the Works team. There were some minor changes to the 1978 customer cars compared to the World Championship winning 935/77 Works car though. To help reliability the engine was increased slightly to just under three litres, which also meant that the minimum weight of the cars had to be hiked to 1025 kg. The twin-turbocharged engine was good for 675 bhp, which was quite an increase over the 600 bhp achieved by single turbo customer cars of 1977. A total of fifteen 1978 spec cars were built for customers on both sides of the Atlantic.

Ironically the only real opposition the 935/78 privateers faced in Group 5 was the latest Works version of the 935, commonly referred to as the 'Moby Dick'. Porsche recognized the situation and only fielded the amazing 750 - 850 bhp machine on very few occasions. The remaining races were disputed between the likes of Joest, Kremer, Konrad and Georg Loos. In particular the Loos car driven by Toine Hezemans proved to be highly successful that season. That season the 935 won all eight rounds of the World Championship and 12 out of the 14 races in the American Imsa series.

Featured is the very first of the 1978 spec customer cars, delivered new to Georg Loos for his GELO team. Effectively the first twin-turbo made available to the public, it was driven with great success by Toine Hezemans, John Fitzpatrick and Peter Gregg. Following in the footsteps of the Works team, this example won the Watkins Glen 6 Hours race in 1978. Restored to the 'Glen winning condition and livery, this highly impressive machine is seen in action during 2007 Nurburgring round of the Classic Endurance Racing series.