Rule changes for the World Championship of Makes eliminated the stunning Porsche 917 during the early 1970s allowing the factory to instead develop the car for the open-top Canadian-American (CanAm) Championship in North America.
Teams from McLaren, Lola and Chaparral were attracted to the 200 mile Sprint races of the formula and the rule book permitted almost anything, including free engine displacement and the use of turbochargers.
Porsche used its new found skills with forced induction to attach two exhaust-driven turbochargers to the flat-twelve engine of the 917. The result had a displacement of 5.4-litres and produced at least 1,100 hp, making it one of the most powerful racing cars ever built. Depending on the boost pressure, the engine’s power output is somewhere between 1,100 hp and 1,400 hp.
With the 917, Porsche for the first time entered the league of immensely powerful, large-capacity racing cars. The 580 hp from the twelve-cylinder 4.5-litre engine of the 917 set new standards, to the extent that even decades later, independent experts rate this Porsche as one of the most impressive sports cars of the century.
Changes in the regulations motivated Porsche to build the 917. Prototypes were allowed a maximum engine size of three-litres, and for sports cars five-litres were allowed. However, a series of at least 25 had to be built. The 1969 race season allowed the 917 to become fully race-proven, with the result that the car entered 1970 with its reliability assured and finely-honed aerodynamics which further improved its track behaviour. At that time, the factory did not enter the cars directly, but via its close partners, John Wyer Automotive and Porsche Salzburg; nevertheless, the World Championship for long distance sports car racing proved to be a triumph for Porsche. Despite fierce competition from Ferrari, the blue and orange, and red and white 917s won almost every race. Continue reading 1970 Porsche 917K ‘short tail’→