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  Porsche 935/78 'Moby Dick'
 

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Country of origin:Germany
Produced in:1978
Numbers built:Two (one never raced)
Internal name:930
Predecessor:Porsche 935/77 'Works'
Author:Wouter Melissen
Last updated:June 08, 2011
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Click here to download printer friendly versionEven though the various variants of the Porsche 935 were out decimating the opposition in the Group 5 class, Porsche's engineers at Weissach continued the development work. For the 1978 the Norbert Singer led team produced the most extreme 911-based racing car yet. While still built to the Group 5 regulations, it was also developed for a potential outright win at Le Mans against bespoke prototype racers.

The first order of business was a thorough redesign of the engine. The Porsche 911 Turbo based, air-cooled flat 6 was already pushed beyond its limits, resulting in reliability issues. For homologation purposes, the crankcase, crankshaft and cylinders could not be changed. Instead the attention focused on the cylinder heads, where there was plenty of room for modifications. The original air-cooled, single overhead camshaft heads were replaced by all new water-cooled heads that sported twin camshafts for each bank of cylinder. These were originally developed for twin-cam variant of the Porsche 908 engine back in 1970 and were also fitted to the latest version of the successful 936 prototype racer.

The departure of the traditional air-cooled heads was prompted by the use of the twin overhead camshafts. There was no other way to cool the spark-plugs, which were no longer mounted in the air-flow but nestled between the two camshafts. What remained was a separate head for each cylinder. These sported four valves per cylinder for optimal breathing. Ultimately limited by the crankshaft design, the engine displaced just over 3.2 litre. Thanks to the more consistent method of cooling, the compression ratio could be lifted to 7.0:1 from 6.5:1 on the earlier engines. Running at a reliable turbo-pressure of 1.5 bar the engine officially produced 750 bhp at 8200 rpm. For qualifying the boost could be upped to 1.7 bar, which was enough to force 845 bhp out of the six cylinder engine.

Meanwhile Singer had had another good look at the regulations before he started construction of the chassis. He took a standard 911 Turbo shell and cut off everything fore and aft of the cockpit, leaving the bare minimum required for the homologation. On both ends aluminium subframes were grafted to support the suspension and drivetrain. For 1977 the FIA had changed the rules to allow BMW to raise the floor of their front-engined 320i to make room for a bigger exhaust system. Singer exploited this loophole and raised the floor on the new 935 as well. While at it, he replaced the steel floor he cut out with a much lighter fibreglass copy. There obviously was no exhaust to route under the floor, instead Singer dropped the suspension, lowering the car by 75 mm without breaking the homologation requirements.

Although widened and strengthened, the suspension was of a similar design as the earlier 935s. At the rear bespoke aluminium suspension arms were fitted to make room for massive 19-inch wheels. The overall lowering of the car also necessitated the four-speed gearbox to be mounted upside down. This considerably decreased the angle at which the driveshafts had to work under. Taking into consideration the turbo-equivalency factor of 1.4, the 3.2 litre engine placed the new 935 in the over four-litre category. The weight minimum in this category was 1025 kg, which placed additional emphasis on the brakes. New vented and cross-drilled discs were fitted that even eclipsed the ones fitted on the purpose-built 917 prototype racers.

As with the chassis, only the core elements of the road car body had to be reused. This gave Porsche's engineers absolute freedom to craft new nose and tail sections. The result was a very sleek and wide design that bore little resemblance to any other Porsche product. The massive front and rear overhangs made the 935/78 much more efficient at high speeds than its predecessors. Another novelty was the big rear wing mounted on struts at the edge of the long tail. The radiators for the cylinder heads were mounted ahead of the rear wheels and fed through large intakes in the fenders. Originally the doors were fitted with shells, connecting the front and rear wheel-arches. This did not get the FIA scrutineers' approval, who mandated the use of the original doors, resulting in an odd looking gap between the fenders.

In a simple white livery, the first 935/78 was sent to Paul Ricard for testing. It was quickly given the nickname 'Moby Dick' after the white whale that starred in Herman Melville's novel with the same title. The early test sessions were far from trouble-free with the all new engine causing the engineers many headaches. With the sight set firmly at Le Mans, Porsche decided to sit out most of the World Championship rounds. There also was little point in competing in these events as Porsche would race primarily against its own customers. At the Silverstone 6 Hours, 'Moby Dick' was given its single outing ahead of Le Mans. Jochen Mass and Jackie Ickx were nearly two seconds a lap faster in qualifying and won the race with a seven lap margin over a privately entered 935.

Owing to the troubles in testing, only a single 'Moby Dick' was fielded in the 24 Hours of Le Mans. It immediately showed its potential by flying along the Mulsanne Straight at a startling 365 km/h. Surrounded by purpose-built prototype racers, the 'production' 935/78 set the second fastest time in qualifying. During the race Rolf Stommelen and Manfred Schurti were once more confronted with teething engine problems. It suffered from a misfire for most of the race and with a third to go an oil-leak was discovered. The two Germans nursed the car home in eighth. After the race, it was found to be a minor problem that would most likely not have caused any problems. After Le Mans, 'Moby Dick' was fielded only twice more, retiring from the lead on both occasions.

At the end of the year, Porsche announced its withdrawal from racing, effectively ending the 935/78's racing career. It is believed that Porsche built one complete car and a spare chassis intended for use in 1979. The completed car has taken pride of place in the Porsche factory museum while the spare was eventually sold and only recently built into a complete car. In 1981 Reinhold Joest used Porsche drawings to build his own 'Moby Dick' but he did not have the benefit of the sophisticated engine. By then many others had followed Porsche's example and two Joest cars could do no better than several second place finishes in the IMSA series. Ironically one of them was involved in a fatal accident that took the life of one of 'Moby Dick's' original drivers, Rolf Stommelen.

Despite the debut victory, Norbert Singer's brilliant machine in the end proved to be flawed. The program was nevertheless far from a complete loss for Porsche as the four-valve engine would go on score outright wins in all major sports car races in the back of the 936, 956 and 962 prototypes. The 935/78 remains as one of the most extreme production based racing cars built and eventually found a successor in the 911 based GT1 cars built late in the 1990s.

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  Article Image gallery (35) Chassis (2) Specifications User Comments (1)