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 tuning, detonation issues, and proposed modifications for a high power cylinder head.
| Identifier | ExFiles\Box 134\2\ scan0001 | |
| Date | 7th January 1935 guessed | |
| To E.P. c. to Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} 1009 1129 Rm{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead}2/GB.2135. HIGH POWER HEAD. The tuning of the above head has been carried to a point at which we can show substantial gains in B.M.E.P. over the 'close-centres' and Standard Bentley Heads (13 and 19 lbs/sq.in. respectively at 4000 r.p.m.). We have had one or two minor but persistent troubles connected with the inlet valve; we have broken two inlet valves and three inlet valve springs. We are worried, however, about detonation on this head. At the low speeds it is better than the Bentley but instead of the detonation disappearing entirely at the higher speeds it goes out over a narrow range of speed and comes back steadily getting worse at about 3200 r.p.m. and then gradually dying away again. We have not been able to alter this characteristic by exhaust valve variation, by changes of mixture or by ignition advance and feel that our only method of taking advantage of this improved performance without detonation handicap is to try the effect of an aluminium head in the expectation that the improved conductivity will modify the characteristic sufficiently. Will you please make the necessary alterations to the drawings and put one of these heads in hand, please. ---------------- Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead} Troubles cured. | ||