In 1967, the Commission Sportive International, the competition arm of the FIA, changed the rules for Group 6 prototypes, running in the World Sportscar Championship. Previously, engine capacity was unlimited, resulting in such racing beasts as the 7 liter Ford Mark IV and the 4 liter V-12 Ferrari. Beginning in 1968, the championship would be run by 3 liter prototypes. They also allowed 5 liter, Group 5 cars, assuming 50 units were manufactured.
Porsche made a very expensive and surprising effort to take advantage of this Group 5 rule. The 917 was designed and constructed in just nine months. On April 20th of 1968, Porsche displayed 25 completed 917's to the stunned CSI inspectors. The car is built around a very light (92 pounds) space frame. It carries a 4.5 liter flat 12-cylinder engine mated to a four-speed gearbox. It was capable of running 220 MPH on the Mulsanne Straight.
John Wyer's team, J.W. Automotive, became Porsche's 'Werks' team for 1970. With sponsorship from Gulf Oil, they created a new wedge shape tail for the 917. The transformed car dominated in 1970 and 1971, winning the World Championship for Porsche both years.
This car won the Daytona 24 Hours in 1970 with Pedro Rodriguez and Leo Kinnunen at the wheel.
This car was converted to a Spyder configuration by the Porsche factory in 1971. It was driven by Leo Kinnunen tot he 1971 Interserie Championship with podium finishes at Imola, Zolder, Hockenhiem, and Monthery. It won at Imola.