Nine seventeen! Two words that spell out the best of the big racing sportscars. Two words that conjure up images of a Pedro Rodriguez Gulf coupe averaging over 160 mph at the formidable Spa-Francorchamps circuit in 1971. Langhecks (longtails), running at over 240 mph down the Mulsanne straight at Le Mans; eleven hundred horsepower unleashed in a bellowing, flame-spitting, turbocharged monster at Laguna Seca in Can-Am. Surely there has never been a more awe-inspiring sports prototype than the Porsche 917
Built around a multi-tubular aluminum space frame, titanium and magnesium alloys were used extensively for the lightest weight possible. Run by a team headed by John Wyer and sponsored by Gulf, 917 coupes won the World Championship in 1970 and 1971, easily beating Ferrari’s 5-liter Sports prototypes, the 512S and 512M.
After the 917 Coupes were outlawed via a rules change, they found a home in the Can-Am series, first as a normally aspirated “PA” Spyder and later as turbocharged 880hp bombshells. Swiss ace Jo Siffert had run a normally aspirated 917 in the Can-Am in 1969, but realized that the car lacked power when matched against the all-conquering big-block Chevrolet- engined McLarens. The 917/10 was the result of the Porsche factory seeking more power from its “Typ 912” flat twelve engine. Although they tried a flat 16 engine of 7.1 liters producing 880 hp, turbocharging the smaller engine offered the potential for even greater power.
The car shown here is the 917/10 that Jo Siffert tested at Hockenheim on July 8, 1971 under the watchful eyes of Porsche Motorsports boss Ferdinand Piech and Development Engineer Helmuth Bott. Jo Siffert was given the car to use as long as he bore the costs of campaigning it in the USA.
The car was delivered to Watkins Glen for the Can-Am race of 25 July, finished in brilliant Day-Glo orange and STP stickers to recognize Siffert’s new sponsor. With little practice, Siffert finished third. He went on to bring the car home in the top five in the remaining Can-Am races, including second at Mid-Ohio and Road Atlanta, fourth in Edmonton, and fifth places at Donnybrook and Laguna Seca. Siffert discovered the 5.0 liter 917/10 Spyder was the equal of the field except for the works McLarens.
Sadly, Siffert was killed in October 1971 in a non-Championship GP race at Brands Hatch. The 917 was returned to Porsche and became the test bed for developments of the turbocharged flat-12. Under the direction of Klaus Bischof, factory race mechanics brought the car up to the latest specification with numerous changes in the interests of better driveability and even more speed.
Willi Kauhsen purchased the modified 917 from Porsche in the spring of 1972 for $62,500. His place was to race in the Interseries, the European equivalent of Can-Am. Kauhsen obtained sponsorship from Bosch and with the car now painted bright yellow, started the season at the Nürburgring and was blindly quick, finishing in second place. He won the next race at Imola in Italy, but retired at Silverstone. He finished second in each of the next four races. The only other car to stay ahead of him was the 917/10 of the 1971 Interseries Champion, Leo Kinnunen.
At the final race of the season in September back at the Nürburgring, Kauhsen crashed. He put the damaged car into storage for twenty-six years. Finally, a meticulous restoration was undertaken by a team of former race mechanics from the Weissach works with assistance from Gustaf Nietsche and Claus Bischof, head of the Porsche museum. The rebuild returned the car to the specification it had run with Jo Siffert in the 1971 Can-Am championship.