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).
Analysis of potential improvements to engine head, valve, and camshaft design for increased power and efficiency.
| Identifier | ExFiles\Box 17\6\ Scan143 | |
| Date | 24th August 1933 | |
| -9- He/Std.11/MA. 24.8.33. (4) The inlet valve size of the standard Rolls-Bentley head can be usefully increased to give a definite increase in power. (5) The present design of both Phantom and R.R. Bentley inlet ports, valving and combustion chamber can be greatly improved to obtain high performance if this is required from these engines - the gas passages are too long and curved in the wrong direction, while the valve itself is robbed of a large portion of its efficiency by the masking effect of the present form of combustion chamber and disposition of valves. Comparison with the 8 litre Bentley "single port" head shows this up very clearly. (6) The volumetric efficiency of the Phantom engine can be increased only slightly by using a longer duration camshaft etc., - with a consequent large drop in low-speed power. (Comparative power curves of a normal duration camshaft E.82445 and a long duration camshaft - Hs.{Lord Ernest Hives - Chair}962 are shown on attached Curve 14). This indicates that we have for the moment about exhausted the possibilities of camshaft with the existing R.R. head design. Hs{Lord Ernest Hives - Chair}/C.S.Steadman. | ||