gently upswept tail was one of the contributors to the search for better handling of the 917 coupés, resulting in the 917K variant. 1970 917K: The 917K was an evolution of the original 1969 car. After the first 917s were run in 1969, it was clear the car's aerodynamics made it nearly undriveable at higher speeds. After the 1969 championship season had finished, John Wyer requested a 3-day test session at the Austrian Österreichring course. The Porsche technical team turned out ready to do some serious panel work on the coupé and in order to make a comparison, brought along the Can-Am 917PA Spyder. The drivers present instantly preferred the PA and together, the JW Automotive and Porsche engineers came up with the idea of a more upswept tail (as on the 917PA). The JW team had had similar high speed handling problems with the early Ford GT40 models. With gaffer tape and aluminium sheet, a completely new short tail was evolved at the racetrack. This was quickly converted into a 'production' design back at Porsche and the 917K (Kurzheck) made its public debut at the season opening 1970 24 Hours of Daytona. Such was the improvement in the stability of the car at high speed, the 917K became the standard configuration for all races except Le Mans, the Nürburgring 1000km and the Targa Florio. This car was raced at every event by JW Automotive and Porsche Salzburg in the 1970 season except the Targa Florio and the Nürburgring 1000 km. The smaller, more nimble and generally better suited 908/03s were used for those races, but privateers used the 917K at the Nürburgring 1000 km, and Vic Elford drove a lap of the 44-mile Targa Florio course in the 917K at Ferdinand Piëch's request. The 917K won 7 out of 10 races; all the races it competed in. Later on in the 1970 season, the 4.5 litre flat-12 was bored out to 4.9 litres, then 5 litres. 1970 917L: This long tail, low drag version of the 1969 917L was purpose-built for the 1970 24 Hours of Le Mans. Le Mans in 1970 was almost entirely made up of long straights and this version was designed to maximise the speed capability resulting from the increased power developed by the flat-12 engine over the previous Porsche types. The 1970 917L was largely based on the initial 1969 car. Nevertheless, factory driver