Rolls-Royce R engine was invaluable in the subsequent development of the Rolls-Royce Merlin engine and the Spitfire. A de-rated R engine, known as the Griffon, was tested in 1933, but it was not directly related to the production Rolls-Royce Griffon of 1939, of the same exact bore/stroke and resultant displacement figures as the "R" design. Three examples of the R engine are on public display in British museums as of 2014. Rolls-Royce realised that the Napier Lion engine used in the 1927 Supermarine S.5 Schneider Trophy winner had reached the peak of its development, and that for Britain's entrant in the next
Rolls-Royce 20/25 Best timed speed: 76.27 mph Maximum Speeds in gears: Petrol Consumption: Driven Hard – 14 mpg The 20/25 engine and chassis were designed for the owner driver market – ideally fitted with a smaller sedan or coupe body as the one used in the 1935 Autocar Test. Unfortunately many 20/25’s were fitted with larger and heavier limousine bodies which hurt their performance. Only the chassis and mechanical parts were made by Rolls-Royce. The body was made and fitted by a coachbuilder selected by the owner. Amongst the most respected coachbuilders who produced bodies for Rolls Royce cars are Park Ward,