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).
The development and performance of a single cylinder Bentley unit with a high power head.
| Identifier | ExFiles\Box 134\2\ scan0014 | |
| Date | 27th May 1935 | |
| Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead}2/GB.27.5.35. SINGLE CYLINDER BENTLEY UNIT WITH HIGH POWER HEAD. Period covered by this report - 1st December 1934 to 16th May 1935. This engine has completed a further 89 hours 10 minutes running time since the last report was issued. The work carried out during this period consists of development work on the 'High Power' type cylinder and heads (Lec's.4075, 4123, 4157), in which the inlet valve (or valves) is placed in the cylinder head immediately above the piston, and the exhaust valve is in the cylinder block at the side of the cylinder proper. A considerable amount of work on detonation has also been carried out with this cylinder and head in order to eliminate high speed occasional detonation. S U M M A R Y. POWER OUTPUT OF HIGH POWER HEADS. When compared with the standard Bentley cylinder head, the High Power head gives a very considerable increase in M.E.P. at all speeds. Taking the best figures, obtained with the twin inlet valve head, a gain of 11.0% at 1000 R.P.M., 7.5% at 2000 R.P.M., 12.5% at 3000 R.P.M. and 28% at 4000 R.P.M. is obtained. Owing to the very free induction of the high power head, the duration of lift of the inlet valve is much less than that used on the standard by approximately 25° (flywheel). DETONATION WITH HIGH POWER HEADS. These heads are peculiar in that they promote intermittent detonation of a severe nature at comparatively high speed, yet at low speeds the detonation is only slight. This refers mainly to the single inlet valve head. A | ||