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).
Comparing inlet valve to piston area ratios across various engine cylinder heads.
| Identifier | ExFiles\Box 134\2\ scan0011 | |
| Date | 26th April 1935 | |
| To Wd.{Mr Wood/Mr Whitehead} from Hs{Lord Ernest Hives - Chair}/Smth. Hs{Lord Ernest Hives - Chair}/Smth.15/KW.26.4.35. Cylinder Heads for Car Engines. --------------------------- On looking into the question of the best cylinder head for future engines, we find the values of the ratio Inlet Valve Area to be as follows for Piston Area various cases which we have tried :- | Head | No. of Inlet Valves | Inlet Valve Throat dia. | Inlet Valve Area / Piston Area | |---------------------|---------------------|-------------------------|--------------------------------| | Standard Bentley | 1 | 1.400 | .176 | | Large Valve Bentley | 1 | 1.500 | .203 | | Ramp | 1 | 1.500 | .203 | | High Power | 1 | 1.750 | .278 | | High Power | 2 | 1.225 | .267 | | Phantom II | 1 | 1.900 | .190 | | Peregrine | 1 | 1.200 | .183 | | Kestrel 1B | 2 | 1.625 | .199 | | Rudge Motor Cycle | 2 | 1.200 | .246 | | ||