F2 started to decline with the arrival of the 2.5 L Formula One in 1954. A new format of Formula Two was introduced for 1957 with 1.5 L engines. This became dominated by rear-engined Coopers and "Bobtail" sports car. Porsches cars based on their RSK sports cars enjoying some success. Ferrari originally developed their 'Sharknose' Dino 156 as an F2 car. The dominant engine was the Coventry-Climax FPF four cylinder.