Mercedes wanted a 320 bhp engine based on the 136 bhp Mercedes M102 2.3 litre 4-cylinder engine. The task was given to Mike Hall, who design the famed DFV and BDA engines. Designed around the existing M102 engine, its valves set a 45° angle, rather than the 40° of the BDA. The valves were the biggest that could be fitted into the combustion chamber. Flat top pistons gave a 10.5:1 compression ratio. The new Cosworth WAA engine also was Cosworth’s first one-piece head. The camshaft carrier was cast with the head itself.