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Dans l’évocation cinématographique de cette course prestigieuse, la réalité et la fiction se croisent sans cesse et les séquences réalisées à bord d’une voiture qui a réellement participé à la course apportent vraiment un réalisme incomparable à l’histoire qui est racontée à l’écran. Une impression renforcée par le fait que Steve McQueen, qui interprète le héros du film, est un pilote chevronné et talentueux.
The 917 is the masterpiece of engineer Ferdinand Piëch and certainly the most successful of all racing Porsches. © IXO Collections SAS - All rights reserved. Photo credits © Archives & Collections Dominique Pascal
At the end of 1967, Porsche already had a good track record in competition and won most of the major Endurance races such as the Targa Florio, the 1000 Kilometers of Monza or the Nürburgring, thanks to the 907 and 908 models. But the most prestigious race of all, the 24 Hours of Le Mans was missing. The following year, engineer Ferdinand Piëch started developing the 917 that would become a big triumph. In March 1968, in order to stem the rise of cars competing in Endurance races, the International Sporting Commission decided to modify the regulations of this category for the following season. Thus, the competitors of Group 6 (Sport Prototypes) see their displacement limited to 3000 cc and those of Group 4 (Sport) to 5000 cc. At the same time, the number of models is reduced by the FIA to 25 instead of the previous double. Porsche seized this opportunity with both hands and in less than a year the 917 was ready, with victory at Le Mans as the first goal.
The impressive cooling turbine covers the flat 16-cylinder, surrounded by bulky detonators. © IXO Collections SAS - All rights reserved. Photo credits © Archives & Collections Dominique Pascal
Extrapolation of the 908
The design of the Porsche 917 began in July 1968 under the leadership of Ferdinand Piëch, head of the competition department, assisted by chassis engineer Helmuth Bott and engine manufacturer Hans Metzger. Eight months later, on March 15, 1969, prototype n ° 001 was presented at the Geneva Motor Show. The first driving sessions took place on the Le Mans circuit on the 29th of March and May 1st, the 25 models of the Porsche 917 were lined up in the factory yard for their homologation. Although the latest Stuttgart car is intended to be marketed as a Grand Touring model, it is nonetheless a true racing prototype in disguise. Porsche is exploiting a loophole in the new CSI regulations that forgot to specify that for the new Sports car category, the engine used should come from the existing series. The 917 was developed on the basis of the 908 from which it is part of the tubular chassis, but this time in aluminum and no longer in steel. To save weight, the chassis side tubes act as an oil line from the front radiator to the rear engine. The platform is covered with a polyester resin body, reinforced with fiberglass, a technique used by Porsche since 1964 (908).
During the 24 Hours of Le Mans 1970, the team of David Hobbs and Mike Hailwood in their 917 KH beats the team David Piper and Gijs Van Lennep. © IXO Collections SAS -All rights reserved. Photo credits © Archives & Collections Dominique Pascal
A unique engine
For its new racing machine, Porsche decides to keep the usual architecture of its engines, namely with the opposing cylinders lying flat and air-cooled. The design time being very short, Metzger took the 8-cylinder 3-liter fitted in the 908s to which he simply added 4 cylinders, i.e. 1.5 liters more, which remained within the limit of the 5 liters authorized. This engine which has a double camshaft per bank of cylinders is built in modern and light materials: aluminum block and cylinder head, magnesium crankcase, titanium connecting rods, chrome cylinders ... The cooling is provided by a large turbine placed horizontally on top of the engine. The initial power of the first series is 550 hp, 80 more than rival Ford GT 40. It will then increase to 580 hp at 8,500 rpm with a maximum torque of 50 mkg at 6,800 rpm. In 1970, another engine was available, the type 912-10 with 4,907 cc and 600 hp, followed in 1971 by the type 912-11 with 4,998 cc and 630 hp. Two main versions of the Porsche 917 are produced with mainly two types of body. The 917 KH short tail version (Kurz Heck), which represents the majority of cars built, is particularly suited to "slow" circuits with few long straights. For the 24 Hours of Le Mans, which at the time allowed high top speeds, Porsche is developing a specific version, the 917 LH long tail (Lang Heck). This model, built in only 5 units, will achieve a feat at Le Mans by setting the best lap time during the April 1971 tests! That day, the driver Jackie Oliver completed a lap in 3’13’600, averaging 250 km / h, and reached a top speed of 386 km / h in Les Munaudières! The 917 LH is distinguished by a longer body of 66 cm and a heavier weight of approximately 20 kg. The lines are more enveloping, with a partial fairing of the rear wheels and gills have been opened above the front fenders for better airflow. The aerodynamic study was carried out within SERA (Société Française Specialized in Aerodynamics) directed by engineer Robert Choulet. The engine is identical to that of the short version, while the transmission has a 5th gear.
The Martini Racing Team's 917 KH, driven by Helmut Marko and Gijs Van Lennep, brought Porsche its second victory at the 1971 24 Hours of Le Mans. © IXO Collections SAS -All rights reserved. Photo credits © Archives & Collections Dominique Pascal
Two main versions
Of the Porsche 917 two main versions are produced with mainly two types of body. The 917 KH short tail version (Kurz Heck), which represents the majority of cars built, is particularly suited to "slow" circuits with few long straights. For the 24 Hours of Le Mans, which at the time allowed high top speeds, Porsche is developing a specific version, the 917 LH long tail (Lang Heck). This model, built in only 5 units, will achieve a feat at Le Mans by setting the best lap time during the April 1971 tests! That day, the driver Jackie Oliver completed a lap in 3’13’600, averaging 250 km / h, and reached a top speed of 386 km / h in Les Munaudières! The 917 LH is distinguished by a longer body of 66 cm and a heavier weight of approximately 20 kg. The lines are more enveloping, with a partial fairing of the rear wheels and gills have been opened above the front fenders for better airflow. The aerodynamic study was carried out within SERA (Société Française Specialized in Aerodynamics) directed by engineer Robert Choulet. The engine is identical to that of the short version, while the transmission has a 5th gear.
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