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).
Comparison of inlet valve to piston area ratios for various eight-cylinder high power engine heads.
| Identifier | ExFiles\Box 134\2\ scan0007 | |
| Date | 11th May 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Rn{Mr Robinson}: 1129 Hs{Lord Ernest Hives - Chair}/Smth.14/KW.11.5.35. EIGHT CYLINDER HIGH POWER HEAD ENGINE. Below are values of the factor inlet valve area / piston area for various heads. [TABLE START] Head | No. of Inlet Valves | Inlet Valve Throat dia. | Inlet Valve Area / Piston Area Standard Bentley | 1 | 1.400 | .176 Large Valve Std. | 1 | 1.500 | .203 Ramp | 1 | 1.500 | .203 High Power | 1 | 1.750 | .278 High Power | 2 | 1.225 | .267 Rudge Motor Cycle | 2 | 1.200 | .246 [TABLE END] There appears to be little possibility of improving the valving on the standard head to give a higher value than .203. A steep angle pent house with a central sparking plug would require two camshafts, and a shallow angle pent house with horizontal plugs would have very little better valving than the present standard head. Regarding the high power head, this can be designed to give an engine which is as short as any other if one push rod only is used to operate each pair of inlet valves. | ||