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).
Letter to Lagonda Motors discussing the weight and performance characteristics of the Phantom III engine unit.
| Identifier | ExFiles\Box 170\1\ img016 | |
| Date | 17th January 1938 | |
| 1104 Rm{William Robotham - Chief Engineer}6/R.{Sir Henry Royce} 17th January, 1938. S.S. Tresilian, Esq., Lagonda Motors Ltd., STAINES, Middlesex. Many thanks for your note and power curve. As I told you, our P.III unit complete with all electrical equipment, flywheel and clutch, clutch casing, trunions, exhaust manifolds and fan drive weighs 880 lbs. This was the original P.III, which is still being sold to the public, but since then we have knocked off the weight about 50 lbs, which I am busy putting back on the flywheel. The standard engine has a 6 : 1 compression ratio which gives 190 B.H.P. and 114 B.M.E.P. We developed a unit @ 6 1/4 : 1, which gives 118 B.M.E.P. and 232 B.H.P. This has rather the Bentley torque characteristics which we are not sure are suitable for luxury motor-cars. It is, therefore, doubtful, whether we shall ever go into production with the increased horse-power. I do not know whether you have ever added up the weight of parts necessitated by a push rod 12-cylinder, which would not be needed with a side valve engine. In the case of the P.III it is about 30 lbs largely owing to the silent tappets. I shall be interested to know whether you managed to silence your engine without a big loss to the exhaust system. When we have got a car for which we do not have to offer a number of apologies I hope to come down and see you. | ||