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).
Performance comparison between long and short duration camshafts at different compression ratios.
| Identifier | ExFiles\Box 102\5\ scan0032 | |
| Date | 26th April 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to Ag. S. c. to Ey. Da.{Bernard Day - Chassis Design} c. to Nor. X5090 Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}1/MJ. 26.4.30. X5090 K5771 LONG DURATION CAMSHAFTS. Previously these have always been compared with the short duration camshafts at the same compression ratio. This is clearly unfair because it means that the long duration camshaft is working with a lower effective compression pressure, at slow speeds. The attached curves and report shew what happens when we bring the B.M.E.P. of the 112° long duration up to that of the 110° short duration camshaft by raising the compression ratio with the former. We cannot get the same B.M.E.P. without slightly more detonation but this can be catered for by ignition timing at low speeds. The tests were conducted on 'China'. We think that on 'Japan', with a low depression carburetter, the 112° long duration camshaft might be useful. Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} | ||