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 Experimental Department responding to Mr. Geoffrey Summers' queries about engine performance issues.
| Identifier | ExFiles\Box 47\1\ Scan230 | |
| Date | 26th January 1926 | |
| To Hm.{Capt. W. Hallam - Head Repairs} from Hs.{Lord Ernest Hives - Chair} c. to BY.{R.W. Bailey - Chief Engineer} X4117 Hs{Lord Ernest Hives - Chair}2/LG26.1.26. 117-MC - MR. GEOFFREY SUMERS. With regard to the points raised by Mr. Geoffrey Summers in his letter of the 23rd.inst. The following is the Experimental Dept's views on these points :- 1. It is probable that it was a broken tappet springs which caused the exhaust valve to stick open. 2. Under the conditions specified in this item, it is not unusual for an engine to go on firing after being switched off especially when the engine has slowed right down and is just about to stop. Investigation has shewn that this is due to spontaneous combustion of the mixture which occurs at very low speeds because there is very little turbulence and the charge picks up a considerable amount of heat from the cyl. jackets, valves etc. 3. Whilst we are satisfied that the plugs we fit will enable the engine to run continuously full power at the maximum speed, there is always a chance of faults developing on plugs. The choice of sparking plugs for an engine is a matter of compromise. The best plug which will not fail from sooting up is one which runs very hot, on the other hand, a plug which is made for the express purpose of keeping cool under full power conditions, will tend to soot up. 4. This could be given attention when the car comes into the Works. 5) & 6) We recommend that we send to this customer a power curve of the Phantom engine, copy of which is attached. He will see from this that there is no advantage to be gained in power in running the engine above 2500 revs. It should be pointed out to the owner that in our opinion, considering the wide range of conditions the car has to fulfil, the Phantom power curve is the best compromise. In cases where it is desirable to go for maximum power, as in the case of aero engines, it will be found that the R.R. engines are as high in performance as any other engine made. Hs.{Lord Ernest Hives - Chair} | ||