How Rolls-Royce improved the Merlin's power output

In the late 1930s, as the ramp head Merlin variant and its development woes were abandoned, it was clear that the engine had huge potential. Here we detail Rolls-Royce's various attempts to increase the power output of its hugely successful engine In late 1937 Supermarine had begun the modification of a ‘Speed Spitfire’ for an attempt on the world air speed record. As with the ‘R’, Rolls-Royce provided support, testing the engine on another of Rod Banks’ special fuels.