Performance improvements for the 25 HP engine, detailing modifications and test results at Brooklands.
| Identifier | ExFiles\Box 5a\1\ 01-page085 | |
| Date | 13th March 1931 | |
| To Sr. From Hs {Lord Ernest Hives - Chair} /Rs. {Sir Henry Royce's Secretary} C. to Wor. {Arthur Wormald - General Works Manager} C. to H. {Arthur M. Hanbury - Head Complaints} C. to PN. {Mr Northey} C. to LP. {Mr Lappin} 25 HP. IMPROVED PERFORMANCE. From time to time we have heard criticisms of the maximum speed of the 25 HP. With a view to seeing what could be done with the minimum alterations to the standard engine to improve the high speed performance of the 25 HP. car, we fitted a new camshaft, stronger valve springs, and higher compression pistons to GLN-60. This engine has been running about in this car for a considerable time and has probably done altogether some 5,000 miles without any trouble. What we claim for this car is considerably increased performance at high speeds (30 m.p.h. and over) with a measured maximum speed on Brooklands of 69.77 m.p.h. over the half mile against a similar type of car with a standard engine 64.29 m.p.h. This we think could be obtained without loss of smoothness now that the larger diameter propeller shaft is standard. The disadvantage of the engine in GLN-60 is that at very low speeds and up to 25 m.p.h. on top gear the pick up is not so good as standard car. Detonation is also slightly worse. We raised the results we have obtained on this engine because (1) Burton writing from America is criticising the speed of the 25 HP. car. (2) We believe that Sales might be glad of this information in case they see any way in which they could take advantage of it in the present difficult times. GLN-60 is always in and out of London and therefore could be tried at leisure. A report on the tests comparing this car with others on Brooklands is contained in Hs {Lord Ernest Hives - Chair} /Rs. {Sir Henry Royce's Secretary} 7/AJ.25.8.30. Naturally further tests would be essential to prove engine life if it was considered worth while. Hs {Lord Ernest Hives - Chair} /Rs. {Sir Henry Royce's Secretary} Att: Extract from Hs {Lord Ernest Hives - Chair} /Rs. {Sir Henry Royce's Secretary} 7/AJ.25.8.30. | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).