70 Years of Porsche – More than 8 cylinders

Many car fans only know Porsche in conjunction with a six-cylinder boxer engine. No wonder, as this is the typical drive in the 911 since 55 years. In the past months, we have shown you that there were different concepts in terms of engine technology available from Zuffenhausen. Starting with the four-cylinder boxer engines of the early days up to the eight-cylinder engines in Cayenne and Panamera there were a lot of interesting cars. And yet we have kept the best for this final part of our little series. Yes, Porsche also built some engines with even more combustion chambers than 8, and yes, also the cars around them were nice and exciting.

917, 917 KH, 917 LH, 917/20

In March 1969, Porsches attack on the upper class of the Sports Car World Championship surprisingly debuted at the Geneva Motor Show. With the new 917, the racing department under the direction of Ferdinand Piëch finally threw a gauntlet to Maranello. After the predecessor types 904 Carrera GTS, 906 Carrera 6, 907, 908 and 910 had prepared the way and were used to gain experiences in lightweight construction of plastic bodyworks, now “the riskiest car of my career”, as Piëch called the 917 years later, followed. Everything about this car was newly developed and planned, from the tubular frame to the wide bodywork to the engine. Hans Mezger designed an 180°-V12 engine with initially 4.5 liters displacement. In some sources, there is the indication that Porsche just used two 911-engines and plugged them together and therefore the 917-engine must be a boxer engine as well. But since in this engine the pistons on their connecting rods opposite each other share a crankpin on the crankshaft, by definition it is a V-type engine. In the boxer engine each cylinder has its own crankpin. Via a center output, which is a centrally mounted gear on the crankshaft, the engine power reaches the gearbox and also drove via additionally smaller gears the four camshafts. In the first stage of development it delivered 520 hp, ready to be released via a manual five-speed transmission.

In order to participate in the largest class of the Sports Car World Championship, the Motorsport Association demanded a minimum number of 25 built vehicles. The proof of which, however, was made sluggish for many manufacturers. Excuses such as: “The remaining ten vehicles are already on their way to the US by ship,” or “we would like to show you the other cars later” (meaning never) were often accepted without asking questions and the homologation granted. Porsche didn’t wanted to do such chitchateas, and already a month after the debut of the 917 in Geneva, the required number of 25 racing cars was parked in front of the authorities in the yard of their plant in Zuffenhausen. There hadn’t been anything like that before. However, the construction of these expensive racecarsput the small brand under financial pressure. Therefore the sale of most copies to private racing teams had been planned from the beginning. This sale process stalled when in the races of the 1969 season major successes were missing and on the contrary the works drivers said, that the 917 was too hard to drive. This was mainly due to the aerodynamics. Originally the 917 received a perspex window over the engine and was available with two different rear designs, which could be quickly exchanged. While the short-tail version (Kurzheck) was intended for tight, angular racing circuits, the long-tail version (Langheck) allowed more topspeed and also generated more downforce in corners via an active rear spoiler that was coupled to the rear suspension.

In fact, the 917 LH reached almost 400 kph at the then chicane-less Hunaudiéres straight in Le Mans during pre-race testing sessions in 1969. But it was all over the place at the same time and so most of the factory drivers asked for the less powerful 908 for the actual 24-hour race. In mid-1969, the FIA prohibited moving wings. At the same time Porsche tested other bodywork configurations in the windtunnel and on Volkswagen’s proving ground in Ehra-Lessien/Germany due to the drivers feedback and finally found the hitherto known option of a short tail with two sharp edges, one above the engine behind the cockpit and the other at the very end of the car. In addition the displacement increased to 4.9 liters and the power to 600 hp. In this version, the 917 finally won in 1970 and 1971 at the legendary 24-hour race in Le Mans and also at various other events. The fins at the rear of the 1971 winning car and its tubular frame made of magnesium showed, that the developers in Zuffenhausen didn’t remain inactive despite the successes. They also re-developed the long-tail (LH) bodywork and even brought the wider 917/20 with the famous ‘pig’ design. Steve McQueen’s feature film ‘Le Mans’ has made the Gulf livery of the John Wyer Racing Team world-famous to this day.

917 Spyder, 917/10, 917/16 Spyder, 917/30

To conclude the racing history of the 917 in the Sports Car World Championship, Porsche in 1971 developed the engine to 4.99 liters (five liters were allowed by regulations) of displacement in cooperation with Mahle, who delivered the Nikasil coating of the cylinders. This engine had 630 hp. However, the special regulations for the five-liter class expired at the end of that year, which meant that 917, Ford GT40, Ferrari 512S and Lola T70 were no longer allowed to race in the World Championship and Porsche had to look for new fields of activity for the 917. Already since 1970 they raced a 917 Spyder, prepared according to Group 7 regulations, in the European Interserie and won it with Leo Kinnunen behind the steering wheel in 1971. Next to that, Jo Siffert raced another 917 Spyder PA in the North American CanAM Championship from 1969. While it wasn’t allowed to start with 4.5 to 5 liters displacement in Europe after 1971, in America it was too small and hopelessly inferior against the 8 to 9 liter Chevrolet V8s. To have at least a small chance at winding circuits, Porsche developed the 917/10 with a shovel-like front spoiler and a wide rear wing for the 1971 season, which was driven to two second places by Jo Siffert.

In search of more engine power, the team around Ferdinand Piëch first went the classic way according to the motto: More is better. Another four combustion chambers were attached to the engine, which increased the displacement to 6.6 liters. On the dyno they achieved up to 750 hp and 735 newtonmeters of torque with this V16, but weren’t able to cure various technical issues there or in the 917/16 Spyder used for testing. Today this vehicle in its innocent white paintwork parks inside the Porsche Museum in Zuffenhausen and scares some visitors when they count the intakes on the engine: “…12, 13, 14, 15, 16, what’s going on here?!?” Everything is alright, only this car has never been used successfully in motorsport and therefore isn’t as well-known as for example the 917 KH. Instead the engine developers pointed out to Mr Piëch that supercharging the twelve-cylinder engine could deliver more power. It quickly became clear that a turbocharger, previously only known from diesel engines in trucks, would release even more power. To be exact, initially the 4.5-liter engine delivered about 850 hp at 1.3 bar of boost pressure. During the second half of 1971, a suitably prepared engine with two turbochargers by Eberspächer was fitted into a 917/10 and sent to Penske Racing for testing with their driver Mark Donohue. In 1972 they took it to racing as well.

This was followed by a period of steady learning to improve the drivability of the turbo and at the same time to be able to better cope with the incipient power explosion once the turbo lag was overcome. For this purpose, Porsche developed and electronically controllable system of control valves, with which the boost pressure could be adjusted by the driver. An adjustment of 0.1 bar corresponded to about 50 hp. During the 1972 season, Porsche increased the engine capacity to five liters and thus achieved up to 1,000 hp. Thanks to a lot of downforce and the high performance, they were superior in the CanAm Championship and won it easily. For 1973, the 917/30 was developed as the final variant of the 917 family. From 5.4 liters of displacement, the V12 now took 1,100 hp an 1,098 newtonmeters of torque. After some more runs on the dyno, Porsche raised this value to 1,200 hp during qualifying, while the test records from Zuffenhausen even displayed 1,570 hp at 2.24 bar of boost pressure. Combined with only 845 kilograms of curb weight, the 917/30 accelerated to 100 kph in 2.4 seconds, to 200 in 5.6 seconds and to 300 in 11.3 seconds. Due to the very high fuel consumption, the car was used in 1973 with a 400-liter fuel tank. For 1974, the CanAm organizers reduced the maximum consumption per race due to the oil crisis and the extreme superiority of the 917/30. Mid-season, the CanAm series was burried after many major sponsors left. So the racing career of the 917 ended. A year later Penske used an aerodynamically optimized car for record runs at the Talladega Speedway in Alabama, where it reached a topspeed of 413.6 kph. This really ended the chapter of 180° V12 engines at Porsche.

Footwork FA12

After Porsche developed a six-cylinder biturbo engine on behalf of TAG and used it successfully from 1984 to 1987 in the racecars of McLaren in Formula 1 (they won three drivers titles with Niki Lauda (1984) and Alain Prost (1985 and 1986) and two constructeurs titles (1984 and 1985)), there were rumors from 1989 about a return of the sports car brand from Stuttgart. In the meantime, the regulations changed from turbo engines to naturally aspirated 3.5-liter motors, which is why a high-revving concept was necessary. In early 1990, Porsche signed a contract with Wataru Ohashi, the owner of the Footwork F1 Team. Until 1989 and again from 1997 this team was better known as Arrows, which is the name that is still better-known to F1 fans. From 1991, they used the new Porsche V12 engine in their Footwork FA12. However, neither the engine, nor the Arrows gearbox or the body were mature enough to get the car into good positions. Several times, the drivers failed to qualify or retired during the early laps of the races. Already in the middle of the season, after the French Grand Prix, Porsche ended the engagement with Footwork and dropped out – although they already had a new engine on the dyno in Weissach. Footwork converted the car to Ford engines and Porsche stored the V12 engines as well as the mentioned new development somewhere in a depot.

LMP2000 (9R3)

In 1998, Porsche achieved the 16th overall victory at the 24 Hours of Le Mans with the final version of the 911 GT1. During their traditional motorsports celebration in Weissach on November 28, 1998, Porsche announced that they wouldn’t compete in Le Mans in 1999. Instead, consideration was given to enter the new LMP prototype category and building a naturally aspirated engine for this purpose. The development of the LMP2000 with the internal abbreviation 9R3 was carried out under Herbert Ampferer. For the engine he looked into storage and found the newly developed engine from 1991. It was a high-revving V10 with 3.5 liters of displacement, which was then adapted to the LMP regulations with an increased displacement of 5.5 liters. At 10,000 revs per minute it delivered 680 hp. Norbert Singer, meanwhile, dealt with a new open body for the LMP concept. At the beginning of November 1999, after a few delays, the car finally hit the test track in Weissach for the first time. Only a few weeks later, on November 21, all development efforts were stopped to concentrate the manpower to the development and market launch of the Cayenne. Thus, the only built LMP2000 rolled into the car storage of Porsche and today is only known to just a few Porsche fans.

Carrera GT

On the eve of the Paris Motor Show 2000, Porsche surprised the journalists with a supercar concept, which was driven by Walter Röhrl in front of the Louvre. Although Porsche boss Wendelin Wiedeking had prohibited the Le Mans project, he wanted to set a strong statement in the supercar market against upcoming competitors such as the then new Aston Martin Vanquish or the announced Mercedes-Benz SLR McLaren. For this he took Harm Lagaay for the design, Norbert Singer for aerodynamics, Walter Röhrl for chassis developing and August Achleitner for the overall development. From 2001, the new Head of Development and member of the board, Wolfgang Dürheimer, joined the group. Two points were quickly established: The new Carrera GT was to be produced together with the Cayenne in Leipzig, but on its own production line and should also be equipped with a carbon monocoque (for the first time in a Porsche production car) and the V10 engine of the LMP2000. Thus, the Carrera GT owes the Cayenne not only the production site in Leipzig, but also the unused engine from the stillborn Le Mans project. This was given a revision for better everyday usability and also grew to 5.7 liters. In addition, the gears for the camshaft drive were replaced by a VarioCam system with timing chains. With 612 hp and 590 newtonmeters of torque, the supercar was a bit less powerful compared to the Mercedes SLR (630 hp) or the Ferrari Enzo (660 hp), which debuted at about the same time. But in terms of curb weight it could score with just 1,380 kilograms. In addition, it was designed transformable with two removable roof parts from Coupé into a Targa. Although originally 1,500 customer cars were planned, only 1,270 copies were produced between the end of 2003 and the middle of 2006.

Since 2006, Porsche hadn’t produced any engine with more than eight cylinders. Thus with the Carrera GT also the history of sports and racing cars from Zuffenhausen or Weissach with large engines ended. Our anniversary series for 70 Years of Porsche also comes to an end now. However, next to the sporty cars with four, six, eight, ten, twelve and sixteen cylinders, there is still one segment of Porsche that we haven’t discussed: the diesel tractors with one, two, three or four cylinder engines, of which about 120,000 copies have been produced from 1950 to 1963. But this is a separate chapter and might be worth another article anytime in the future.

Images: Porsche, Matthias Kierse