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 later taken back by the factory and scrapped. The other two were used for factory transport or display purposes. Rolls ordered three more chassis for delivery in 1906 but there is no evidence these were ever made. No example of a 1905 V-8 car or engine is known to survive. Although the 1905 V-8 cannot be judged a success, lessons learned from the engine were used in subsequent Rolls-Royce engine designs. Having used straight six, straight eight and V-12 engines in the interim period, the need for another new engine was recognised in the early 1950s. Development of a totally