Rolls-Royce Merlin exhaust flow and waste-gates, meant that this option was rejected in favour of the two-stage supercharger. Fitted with the two-stage two-speed supercharger, the Merlin 60 series gained 300 horsepower (224 kW) at over the Merlin 45 series, at which altitude a Spitfire IX was nearly faster than a Spitfire V. The two-stage Merlin family was extended in 1943 with the Merlin 66 which had its supercharger geared for increased power ratings at low altitudes, and the Merlin 70 series that were designed to deliver increased power at high altitudes. While the design of the two-stage supercharger forged ahead, Rolls-Royce also
Rolls-Royce V8 engine new V8 engine began in 1952, bearing no relation to the 1905 version apart from its V8 configuration. Rolls-Royce purchased Bentley in 1931 and the new engine was intended for use in both Rolls-Royce and Bentley automobiles. The result was a series of V8 engines known internally as the "L410", the name relating to its bore size of 4.10 inches, in accordance with the company practice. Despite some attempts at changing the naming convention, the engine has kept both the 4.10 inch bore and the name L410 throughout its life, with the exception of the odd prototype. Continuous improvement saw