beginning of the season. The superior power of the 302 cubic inch (4,942 cc) V8 in the GT40s allowed them to win on fast tracks, and especially at Le Mans two years in a row from 1968 (Pedro Rodríguez and Lucien Bianchi) and 1969 (Jacky Ickx and Jackie Oliver), even though they were outclassed at twistier tracks. It became apparent the GT40 would become obsolete after 1968 as the minimum numbers of sportscars was lowered to 25, a loop hole of which Porsche took advantage by building over two dozen 5,000 cc prototypes that were homologated as sports cars in 1969. The Porsche 917 were fast but in 1969 still unreliable and with bad handling. After the 1969 season, Wyer switched also to the 917 (and 908 for slow tracks), and the JWA team became the factory's main partner. They were a major factor in developing the wedge-shaped Kurzheck tail of the 1970 917K which made the car much more stable than the original 1969 long version. Battling with the works Ferrari 512s, and the other Porsche teams, the JWA Gulf-Porsche 917s, raced by Jo Siffert, Brian Redman, Leo Kinnunen, Pedro Rodríguez, Richard Attwood, Herbert Mueller and Derek Bell, earned seven out of Porsche's nine victories in the 10 races of the 1970 season, and five out of Porsche's eight victories in the 11 races of the 1971 season. During this period, the team's best result at Le Mans was second place in 1971. In fiction, a Gulf-Porsche 917K won in the cult Steve McQueen movie Le Mans, making the Gulf colours even more famous. The rule that permitted 5-litre sports cars like the 917s had been limited to 1971, and the new weight limit for 3,000 cc prototypes was too high for the Porsche 908, removing the 908's advantage that balanced the lack of power of the air cooled 2-valve engine with low weight and good handling. As a result, Porsche left European style sportscar racing to privateers, and focussed on developing turboengines for the 917/10 Can-Am entry, as well as an already 9 year old car: the 911. Wyer adopted the new 3.0-litre regulations and started building Gulf-Mirage prototypes again, using a Formula One Cosworth DFV engine. The successful F1-engine was considered unsuited for endurance racing as vibrations took their toll after several hours, so necessitating modifications. After three years of attempts, Jacky Ickx and Derek Bell achieved