In July of 1968 Porsche began designing and building a new prototype for the Sport category. The FIA changed the regulations of the Sport category to allow vehicles with 5-liter engines, up from the prior 3-liter capacity. Instead of 50 examples, only 25 examples needed to be produced to satisfy homologation rules. With the 917, Porsche had high hopes for capturing an overall victory at the grueling 24 Hour of LeMans. Porsche had seen success with its 904, 907 and 908 race cars. These cars had done very well on the race track though some were plagued with mechanical difficulties and other growing pains which may have held them from realizing their true potential. Porsche had not captured any overall wins at LeMans just victories within their classes.
The Porsche 917 was designed and built in 10 months and was powered by the Type 912 flat 12 engine of various different displacement. Throughout its life span it would be outfitted with a 4.5, 4.9, 5 and 5.4 liter engines. The front suspension was independent by unequal control arms with coil springs over tubular shocks. The rear was also independent by unequal control arms and radius rods with coil springs over tubular shocks. There were disc brakes place on all four corners and featured a Porsche 5-speed manual gearbox and an aluminum tube space frame chassis. All 917's were right-hand drive. There were various body configurations including the long-tail and short-tail.
On March 12, 1969 the Porsche 917 was displayed to the public at the Geneva Auto Show. It had been painted white with the front of vehicle painted green.
Inspectors came to the Porsche factory to verify that the 25 necessary vehicles had been built. Unfortunately only three had been assembled. There were nearly 20 other examples in the process of being assembled and parts for the remaining available, however, Porsche was denied the homologation. Near the end of April all 25 examples were assembled and on display for the inspection team. It was finally cleared for racing in the Sport category.
Chassis 010 was sold to David Piper, 007 went to Gesipa Racing Team, 021 to Aarnio A. Wilhuri who had Shell Sponsorship, 018 to Alex Soler and 025 to Dominique Marin of Zitro Racing. In 1970, atleast 20 other examples of the 917 were manufactured.
As with most prototype vehicles, the 917 suffered from growing pains. The aerodynamics created low drag rather than down force and made the vehicle unstable at speeds.
In 1970 an partnership was reached with John Wyer and the Gulf Team. Wyer had won the LeMans in the past driving the Ford GT40 with sponshorship through Gulf Racing. Porsche extended an offer to Wyer that if he could keep his Gulf Racing sponsorship, Porsche would provide 3 cars per race plus its two best factory racers, Jo Siffert and Brian Redman. It was John Horsmann, an engineer for John Wyer, which suggested that low drag be sacrificed in place of downforce. A tail was conceived and placed on the rear of the 917 Short tail. This greatly increased the stability of the vehicle at speeds. The vehicle was then dubbed the 917 K, representing Kutz or short-tail. The side exhausts were removed and the front of the vehicle was modified. Another low-drag version of the 917 was created specifically for Le Mans. The 917 LH, meaning langen and German for long, was given a Long Tail body. When compared with the 1969 version, was much safer and more stable.
During the 1970 LeMans, two 917L's were entered with seven 917K's. There were two engine sizes used, the 4.5 and the 4.9 liter. Chassis number 004, the number 20 Porsche 917K, was driven by Siffert and Redman and used the new 4.9-liter engine. It had qualified in 3rd but was retired after 156 laps due to a blown engine. Chassis 021, number 18 using a 4.5-liter engine, was entered by David Piper and Gijs van Lennep and qualified 11th. After 112 laps, Piper suffered a tire puncture and crashed the car. Number 21 driven by Rodriguez and Kinnunen, suffered a broken connecting rod. At 8:30 am an inlet valve broke and KG Salzburg lost its best car, the number 25 driven by Elford/Ahrens. Chassis number 026, the number 22 4.9-liter Porsche 917K, was a JWA Gulf vehicle driven by the motorcycle champion Mike Hailwood and David Hobbs. The vehicle had qualified 10th and after only three hours was running in third place. Unfortunately, an Alfa Romeo T33/3 driven by Carlo Facetti spun and hit a wall and Hailwood was unable to evade the accident. KG Salzburg chassis number 023 driven by Hermann/Attwood, a 917K using a 4.5-liter engine, captured first place and Marini 4.9 Porsche 917LH chassis number 043 captured second, and five laps down from the first place car. Chassis 043 was driven by Gerard Larousse and Willi Kausen.
KG Salzburg retired from competition after the season.
For the 1971 season and in preparation for the LeMans race, Porsche performed testing and studies to make the 917L more stable. Three 917L's were entered. The factory backed number 22, the Martini International Racing Team, and two John Wyer Gulf Racing 917s. The Gulf cars were numbered 17 and 18 with the #18 vehicle capturing the fastest time during qualification. The Martini Racing team won the 24 Hours Race of LeMans with Austrian Dr. Helmut Marko and Dutch Guijs van Lennep as the drivers.
During the 1971 season, Porsche had won 8 of the 11 rounds of the Manufacturer World Championship.
At the end of the 1971 season the Porsche 917 and Ferrari 512 had proven their abilities and supremacy that the FIA added new regulations that made them ineligible to race in world championships.
The 917/10 was similar to 917 but purposely built for Group 7 of American CanAm racing. It used even more lightweight materials and a larger fuel tank. The larger tank allowed the vehicle to complete a 200 mile race without needing to refuel. During its first season of racing, it was not as successful as hoped. The 12-cylinder engine was not powerful enough to compete for first place. So the 917 was fitted with turbochargers. With the turbochargers and 950 horsepower, the driver needed to be very cautious due to the sudden power increases produced by the turbochargers.
During the 1972 season Mark Donohue and George Follmer drove the Porsche's in competition. Donohue was faster but due to an accident was unable to complete the season. Follmer was left to capture the championship, which he did.
In 1973, the 917/30 was outfitted with twin-turbochargers and a 5.4 liter, 12-cylinder engine. It was capable of produced between 1100 and 1500 horsepower. It could go from zero to sixty in 2.1 seconds and had a top speed of 238 mph. The 917/30 was only available for Team Penske's driver Mark Donohue. It dominated and demolished the Can-Am series with Mark Donohue winning the championship.
In 1974 it was banned from racing in the CanAm series because the CanAm series had begun to lose its fan base since there was no competition.
The Porsche 917, a fantastic car, could be beaten and this was proven. The records that it set were broken by smaller, lightweight prototypes such as Ferrari and Alfa Romeo in the years that followed. When the 917's won, it was because they were the fastest at the time or the faster vehicles had suffered DNF's. It was the 917/10, 917/20 and 917/30 that truly dominated the racing circuit and were unbeatable. Many of the records that were established still exist today. With over a thousand horsepower, backed by a company that had years of racing experience, and driven by some of the greatest drivers at the time, the vehicles were dominate.
The Porsche 917 played a staring role in the Steve McQueen movie, 'Le Mans'.
by Dan Vaughan