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).
Technical memorandum discussing proposals for increasing the performance of the 25 HP car.
| Identifier | Morton\M9\ img014 | |
| Date | 5th August 1931 | |
| SPEED' FILE ORIGINAL To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} K.{Mr Kilner} c. Dn. RV. HsL/AM5.8.31. INCREASED PERFORMANCE OF 25 H.P. x.5771. X.5010. If we can offer a 25 HP. car which has a maximum top speed of 75 M.P.H. it should help sales. Personally, we know of several people who would probably buy a 25 HP. car if the performance was improved. There is very little design work necessary and there is very little alteration from standard parts. If we take the car which has run on Brooklands with the standard R.R. carburetter, there is only one feature which prevents us selling these cars and that is, we must have balanced crankshaft. Firstly in order to reduce wear and secondly to improve smoothness. We have a W.W. design for a balanced shaft and one is being prepared. The recent tests which have been carried out show that if we completely balance the shaft and big end we should get a smoother engine than the 8 balance scheme which is fitted to 16-GIV now at W.W. We cannot do this with the present diameter of shaft because we shall reduce the main torsional period into the range of running. We suggest, however, there is a possibility of increasing the diameter of the journals so that they can still be got into the present crankcase. Another feature we should like to see incorporated in the 25 HP. is a flexible coupling between the engine and gear box. On all cars we are always more or less on the verge of gear box rattles and the clearances have to be kept very close in the different parts to prevent these being objectionable. The engine unit with cast iron crankcase and cylinders in one has the merit of producing a particularly smooth engine. Originally this engine was running with much higher compression than standard and it was remarked upon as being particularly smooth. Since then it has been rebuilt with parts changed over from an engine which was complained of for roughness but the cast iron unit still remained smooth. It may be that with a completely balanced shaft, we shall obtain the same smoothness with the standard crankcase but we think it is worth while putting on record that we have found certain virtues in the cast iron construction. Hs.{Lord Ernest Hives - Chair} | ||