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Porsche 935 nicknamed Moby Dick

Porsche 935/78 ‘Moby Dick’ and Project ‘Typ 935/80’

The Leviathan

From 2022 onwards, GT cars in endurance racing will be built to GT3 regulations, which means they’ll be technically less sophisticated than the current GT2-based cars, but above all, should make them cheaper to develop, produce and run. Some forty years ago, however, the Group 5 regulations for GT cars were almost as liberal as one could dream, and the only real limit was the car designer’s technical insight, curiosity and imagination. At Porsche, technical designer Norbert Singer had all three in abundance.

by Serge Vanbockryck

After the World Championship for Makes (WCM) – predecessor to the WEC – had deflated like a Yorkshire pudding in the first half of the 1970s, new rules were required to revive the championship and rekindle the interest of the manufacturers again. Thus in 1976, under pressure of the West-German manufacturers, the emphasis would be on proper, volume-produced GT cars, like the Porsche 911, Ford Capri and BMW 3.5CSL. The new-generation race cars were referred to as ‘silhouettes’, the more commercial-sounding name for what was technically known as ‘Group 5’. 

While these cars would retain the shape – or silhouette – and basic architecture of a production GT car, the technical rules allowed for some liberal changes, especially on the engine and aerodynamic side of things. The engine had to stay in the same position as on the homologated road car, but it only had to retain the original block while turbochargers or superchargers could be added. Minimum weights were defined by engine capacity whereby turbocharged engines would have their swept volume multiplied by 1.4 so as to not disadvantage normally-aspirated cars. 

As for the bodywork, all four fenders could be flared to accommodate (much) wider wheels, while spoilers, splitters and wings could be added. Doors, engine cover and bonnet, as well as the windows, could be made of other materials, as long as they remained interchangeable with the original parts. In other words, a rear wing could be added to the 911’s engine cover as long as an original part would still fit snugly in place on the Group 5 version of the car. Giant rear wings like that on Porsche’s 1974 Carrera RSR were banned by the CSI (the Commission Sportive Internationale, precursor to the FISA) by fine-tuning the regulations so that now the rear wing support had to stay within the vertical shadow of the wing, and stipulating that the wing could not pass the outline of the frontal area; in other words, it should not be seen when the car was viewed head-on.

Porsche’s new technical director in charge of road car-based race cars, Norbert Singer, probably knew better than any of his contemporary colleagues how to read the rules and regulations, and especially how to read what was not written. When the Porsche 935 made its debut in Mugello in 1976, it immediately caused a stir at scrutineering for the headlights had been relocated to the front fender, resulting in an aerodynamically much smoother front end which reduced drag and also produced more downforce. The scrutineers didn’t like it at all. However, with nothing in the rules relating to the shape of the fenders, they were forced to concede that it was legal. It wasn’t Porsche’s fault that they were the only ones with headlights sitting in the fenders while the other cars’ headlights sat in the radiator grille. By the end of the 1976 season, the rear fenders had been lengthened and sculpted to mimic an integrated wing shape, further increasing the aerodynamic efficiency of the car. Porsche won the championship from BMW at the final round in Dijon and while the boys from Munich persisted with their new 3 Series replacing the CSL, the Ford decision makers in Cologne decided to stick to the German national DRM championship instead and not to bother with trying to beat Porsche on the world forum.

For the 1977 season, Singer figured that the best defence was to attack and further improved what already was the most competitive Group 5 car by a country mile. Refinements to the aerodynamics included a completely revised front end with rear view mirrors integrated in the fenders. Those front fenders, as well as the rears, had again increased in size and were now connected by so-called ‘running boards’, while the rear fenders were stretched further back, effectively turning the 935/77 into a Langheck (Long tail). The rear wing assembly was of a completely new and extremely intelligent design. Singer’s clever reading of the rules had produced a second rear window sitting several inches above the original one, effectively raising the roofline and connecting it with the engine cover in one, smooth and more horizontal plane, thus feeding cleaner air to the revised rear wing. This Singer could do as the rules stated that any aerodynamic device at the rear of the car was accepted on the condition it did not exceed beyond the profile of the car when viewed head-on. It was, however, highly unlikely the CSI rules makers had double roofs and ditto rear windows in mind when they wrote that particular rule. 

Porsche 935/77

Caption: Porsche 935/77. Note the rear view mirrors integrated in the wider front fenders which are in turn connected to the rear fenders by so-called ‘running boards’ 

The engine for the 935/77 was the air-cooled Typ 930/78, still with a 2,806cc capacity like the Typ 930/72 from 1976, but with two smaller KKK turbochargers instead of one, each with its own waste-gate. A new water-cooled intercooler now sat in front of the engine, after the CSI had issued a rule saying that the firewall between the engine compartment and the cockpit could be moved forward by 20 centimetres. The new package was good for 630bhp at 8,000rpm, an increase of some 40bhp over the previous year’s model. With the increase in power in mind, Porsche sought to improve the brakes by installing a servo between the brake pedal and the dual master cylinders. Interestingly, this was discarded during the season as it appeared to double the brake pad wear on the Typ 917 brakes. Power steering was also tested, but not used in races. The 935/77’s season was one of ups and downs, with as many wins as DNFs – mainly due to engine-related issues. But Porsche again won the world championship thanks to a flotilla of privateer 935s.

A matter of words

Long before the 935s started dominating the 1977 WCM season, however, the CSI had agreed to some technical leniency towards Ford and BMW, at the specific request of the latter, but only if the other manufacturers, i.e. Porsche, also agreed to this rule change. Thus, at a meeting at the end of 1976, the CSI Technical Subcommittee and the manufacturers’ representatives agreed to allow the floor pan of the cars to be cut and raised. BMW, and also Ford, felt they were disadvantaged by the fact that they ran front-engined cars which meant that they had to run increased ride height to allow for the exhaust, muffler and heat shields under the cars’ chassis. As such, they were indeed disadvantaged vis-à-vis the Porsche, which could be run as low as the rules permitted since engine, turbo and exhausts all sat in the back.

Porsche valiantly agreed to this new rule, and the CSI, as well as Ford and BMW, were quite pleased by Porsche’s gentlemanly gesture for the better of the championship. However, they didn’t realise they had just let in a Trojan horse. Singer – clearly in a league of his own when it came to fast forward thinking – had his own use for the new rule. ‘The approved wording of the regulation was not specific to the exhaust and it gave us the opportunity to cut the side panels of the 935 and lower the whole car,’ he says. ‘We made a new floor with an aluminium frame and glassfibre sandwich and lowered the 911 chassis height by 60mm to 1110mm.’ Thus was born the first spaceframe Porsche 935.

Fifth-scale model of the Porsche 935

Caption: Fifth-scale model of the Porsche 935/78; nose of full scale mock-up on the right in the background. Smoking on the work floor was no problem in 1978!

slick body buck of the 935/78 on an older model 935

Caption: Shaping the very slick body buck of the 935/78 on an older model 935.

Building the 935

Caption: Building the 935/78. Note the black roof and A-pillars of the road car; the only original body parts of the road car.

The height of the new 935/78, however, was the only size that decreased, as every other measurement was seriously increased. The front track grew by 128mm to 1630mm, while the rear track was increased by 17mm to 1575mm. Entirely built for speed on Le Mans’ six-kilometre Hunaudières Straight, the car also received a tail 21cm longer than the previous model, with a low rear wing sitting across the entire width of the car. The first iteration of the wing was supported by end-plates attached to the outer fenders.

The doors were now completely covered with a widening second skin, effectively linking the outer edges of the front fenders with those of the rear fenders; in effect, a king size NACA duct feeding fresh air to the side-mounted radiators. The front of the car was extended as well, perfectly suiting Singer’s aero needs. The rules didn’t limit the overhangs anyway. The front fenders were given a concave, downforce-creating shape ahead of the actual wheel arches. At the rear, the inclination and size of the chord of the wing allowed for almost as much downforce as one wanted, but adjustable aerodynamic appendages at the front were not permitted, bar for a horizontal splitter. Therefore, to increase overall downforce, Singer looked at ways to increase the figures at the front of the car, but the sculpted fenders ultimately never made it beyond 1/1 scale wind tunnel testing.

Porsche 935, Moby Dick

Caption: First version of the Porsche 935/78: fully covered doors with big NACA ducts and low, full-width rear wing. No points for guessing where ‘Moby Dick’ nickname came from.

For better weight distribution on the clockwise circuits the driver was sitting on the right side of the car, while power was supplied by a specially designed, fully water-cooled, 24-valve, twin-turbo 3,211cc unit with welded cylinder heads, good for some 750bhp at 8,200rpm with 1.5bar boost. Porsche had just created a car nobody had ever envisioned when Group 5 had been established just two years earlier. 

Moby Dick

‘After lowering everything we could on the car, we had to turn the gearbox upside down so that the driveshafts would not be inclined at an impossible angle,’ Singer says. ‘Spaceframes carried the front and rear suspensions and the stiffness of the chassis was increased by more than 40 per cent compared with the 935/76. We had to keep the original doors, but there was nothing that said we could not cover them, so we did. When the FIA delegates (famed technical journalists Paul Frère and Curt Schild) saw the car for the first time, in February 1978, they were completely shocked.’ When the first pictures of the car were published, painted all white with just a few Martini logos, it was immediately given a nickname which would stick forever: Moby Dick, the mythical white whale. But the FIA delegates objected to the fully covered doors so Singer developed an interim solution by covering just half of the doors. 

Singer tried this solution

Caption: After the CSI kicked out the fully covered doors, Singer tried this solution.

At the same time as changing the doors – though not aerodynamically working together – the low and wide rear wing was changed for a more conventional one, narrow and high-mounted. In the end, the FIA back-tracked on the doors, but Singer was happy with the way the car was now and didn’t bother changing them again. There wasn’t enough time to do so before the first race anyway.

Ready for testing

Caption: Ready for testing duty: Moby Dick sits in front of the Weissach buildings. Note period Beetle in the background.

Moby Dick’s first race was the Silverstone 6 Hours, the traditional life-size test for any team serious about Le Mans. Jochen Mass duly put the car on pole position in a new record time, and he and Jacky Ickx disappeared into the distance once the lights went green, winning the race by a seven-lap margin. Le Mans, however, proved to be a disappointment. The high fuel consumption meant that it would have to refuel every ten or eleven laps, and any advantage gained by the car’s supreme top speed – it was the fastest at 227mph (366kph) – would be immediately annulled by the frequent refuelling stops, an estimated 35 stops over the course of the 24 hours. As it turned out, Moby Dick would be plagued by all sorts of smaller problems, such as the throttle not closing fast enough on over-run, a water radiator leaking, the windscreen coming loose, ignition distributor problems, a misfire, an accident and finally an oil leak, all in all resulting in Rolf Stommelen and Manfred Schurti finishing in eighth place overall.

First track tests at the Paul Ricard track

Caption: Moby Dick during first track tests at the Paul Ricard track in France.

Jacky Ickx testing the revised version of Moby Dick

Caption: Jacky Ickx testing the revised version of Moby Dick at Paul Ricard. Norbert Singer stands on the left in white team jacket.

After Le Mans, Porsche decided that it had little left to gain from continuing to compete in the World Championship and that whatever competition there was, would be easily and swiftly dealt with by the Porsche customer cars. The 935/78 appeared only twice more, at the famous non-championship Norisring race in Nuremberg, where Ickx retired, and at Vallelunga, the final round of the World Championship. After some initial set-up problems, Ickx qualified on pole by over two seconds, and he and Schurti comfortably led the race until ten minutes from the end when the injector pump belt drive was cut by a stone. It was an abrupt end to a great success story, for soon afterwards sponsor Martini & Rossi announced they were taking a sabbatical from motorsport sponsorship.

Moby Dick, Porsche 935

Caption: Moby Dick: designed to push the boundaries of speed, and the rulebook.

Vallelunga thus was the last-ever race for a factory 935, and Moby Dick was subsequently mothballed. ‘There were no plans to sell the car to customer teams as long as they would still be competitive with their regular 935s,’ says Singer. And that they were indeed: in 1979, privateer 935s won their class in eight out of nine rounds of the WEC, including overall wins at the Daytona 24 Hours, Mugello, Silverstone, the Nürburgring and Watkins Glen, plus, of course, a shock overall victory at Le Mans. 

Ground effect 935

Unbeknown to most, however, Porsche had looked at returning to the WCM full time in 1980, with a factory team and an über-Moby Dick, the 935/80. The reason for this late development was that Porsche motorsport boss, Manfred Jantke, was convinced BMW were planning an assault on the 1980 WCM with a pair of works-prepared, turbocharged Group 5 M1s. This had Porsche worried since, with no other works teams racing in the over-2,000ccm Division I, BMW could very well score one or two easy world titles in the final years of Group 5, something Porsche would have hated to see happen. Jantke thus ordered a feasibility study to be made by the motorsports department. 

In the summer of 1979 Norbert Singer had been working on the ultimate development of the 935, starting with the sleek 935/78 from the year before. Formula 1’s recent ground effects revolution had Singer thinking along similar lines as Lotus’s Colin Chapman, and the 935/80 was to feature rather extreme aerodynamics. A full-width venturi tunnel was designed to funnel the air from the front of the car, underneath the full-width flat bottom and to the rear. 

wing profile underneath the 935/80

 Fixed skirts and splitters

Caption:  The massive wing profile underneath the 935/80, with fixed skirts and splitters can clearly be seen. The engine would in effect be ‘wrapped’ aerodynamically. 

However, the air would not exit the car from underneath the rear bumper as one would expect. Instead, the wing shape under the car would dramatically curve upwards behind the rear cockpit bulkhead and send the airflow through the top of the car, exiting below the rear windscreen and ahead of the engine. The airflow was then further directed underneath the rear wing, the exact position and shape of which hadn’t been decided yet at the time the project was halted.

The biggest handicap for developing ground effects on the 935 was, of course, the position of the engine. Not only did it sit at the very rear of the car, which would always compromise the ideal airflow, but its boxer architecture also made it wide. Ultimately, the twin-turbo flat-6 would have been shrouded and sealed off from the airflow going underneath the car. How exactly this would have looked wasn’t set in stone yet either. ‘When you worked on a new idea, first of all you had to get the overall idea working and then you optimised it,’ Singer says. ‘Details were worked on later. After that you can check or modify and or adapt the concept to the regulations. This was always my way of doing it.’

The front of the 935/80 was to receive a similarly overdeveloped aerodynamic treatment. Sketches made by Singer show the front wheel arches to be equipped with no less than four adjustable winglets, similar to some of the early developments done on the CanAm-spec 917/10.

Singer sketch 935

Caption: A Norbet Singer sketch showing multiple adjustable winglets built into the front wheel arch area.

Singer took his ideas to the FKFS wind tunnel in Stuttgart for several days in July of 1979. Equipped with the 1/5th scale model of Moby Dick, which had a functional internal airflow to the radiators, he started with the race set-up from the 1978 events to set the benchmark figures for drag and front and rear downforce. Over the course of three days, Singer tried some 45 different combinations to the ground effects theme. The rear wing was inclined at different angles and sitting in various positions and heights; the rear fenders were sometimes equipped with small longitudinal gurneys on the inner edges next to the engine cover; the ride height at the rear was changed… 

Wind tunnel model

Caption:  Porsche 935/80 wind tunnel model with low rear wing over the open engine bay (top); with high rear wing over open engine bay. The air was to be directed from the venturi tunnel under the rear wing (middle); and with the wing moved forward to work with the venturi exiting from under the rear wing (bottom).

The engine, too, would have received the necessary attention from engine men Hans Mezger and Valentin Schäffer, with ideally more power extracted from the flat-6 while also needing less fuel than Moby Dick. For the suspension, too, Singer had some novel ideas, such as a further development of the trailing arms. Alas, the FIA Technical Subcommittee’s Paul Frère, didn’t like it as he didn’t want to open up this area of development any further than the words of the regulations intended.

Design and development work on the actual spaceframe chassis hadn’t started yet when it became clear that nothing was happening in Munich. Work on the 935/80 was subsequently halted, something which Norbert Singer today says he regrets a little. ‘It was a new attempt at making an even better version of Moby Dick. It’s the normal way to further develop a car: the successor should be better, or much better, than the predecessor.’

Thus, Porsche’s 1980 return to the WCM and the successor to Moby Dick would only ever exist on paper and in partially developed 1/5th scale wind tunnel models. And maybe just as well: for what nickname could this magnificent creature possibly have been given?

All images copyright Corporate archives Porsche AG

Other articles by Serge Vanbockryck

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