First models had a 4.5L engine that developed 520 hp. But by 1972, turbochargers have been injected to the 917's engine, to develop up to 1000 hp, and 1200 hp in 1973. Body models were designed differently to meet the demands of different racetracks. So the 917 had many shapes, some with lowered-roof, some with no roof at all.
However, in 1974, disaster! The FIA rules and regulations changed, and put the 917 out of the race. Production since then, ended.
So with 40 years of celebration and giving the fact the Porsche has been involving with new technology like PDK gearbox, which the 917 started all this, Porsche has listed on their website the full history of the 917, and brought some the legendary models to their new museum.
Happy Birthday 917 !