speeds. For 1970, an improved version was raced by the factory and for 1971, after very significant development in the wind tunnel, the definitive 917L was raced by both factory and JW. In 1969 Jo Siffert raced an open-top 917PA Spyder (normally aspirated) in the 1969 CanAm series. There is also the "Pink Pig" aerodynamic research version (917/20), and the turbocharged 917/10 and 917/30 CanAm Spyders. Porsche 917s also raced in the European Interseries in various configurations. In the 1973 Can-Am series, the turbocharged version Porsche 917/30 developed . Variants There were a number of versions of Porsche 917 made over the years; at least eleven different versions have existed. 1969 917: The original Porsche 917 was first run at the Le Mans Test in March 1969 and right from the start showed considerable handling problems due to aerodynamic lift. The original specification of the car included a detachable long-tail (Langheck), that was designed using experience from the previous 907 long-tail coupés for minimum aerodynamic drag, with suspension controlled moving flaps on the tail. At Le Mans the CSI baulked at this, moving aerodynamic aids having been banned in motorsport. It was only when Rolf Stommelen demonstrated how undriveable the car was without the moving flaps that they relented and allowed them for Le Mans only. Throughout 1969 the car's speed was countered by the handling problems and it won only one race, the Zeltweg 1000km. Following that event, JW Automotive, who would be acting as a semi-works team in 1970, requested a test session with Porsche to try and sort out the car's problems. 1969 917PA: The 917PA was an open-topped and short-tailed version of the original 917 and was built to compete in Can-Am racing. Only two cars were built by Porsche. The first never raced, and later became a test mule for an experimental flat-16 engine. The second car was entered in the 1969 Can-Am season by Porsche Audi, the North American distributors for Porsche (hence the PA designation), and driven by Jo Siffert. Compared to the dominant McLarens, the car was underpowered and overweight. Siffert's best result was 3rd at Bridgehampton, and he finished 4th in the championship. For 1971 the car was obtained by Vasek Polak who ran it for the next three years with the car gaining ever more aerodynamic aids, until by 1973 it resembled the 917/10 variant. The design of the 917PA's