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).
Development and testing of a high power single cylinder head.
| Identifier | ExFiles\Box 134\2\ scan0004 | |
| Date | 19th March 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead} [handwritten] 1129 [/handwritten] Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}4/KW.19.3.35. Single Cylinder Work - High Power Head. Confirming our conversation on this unit, we think that the results obtained so far are encouraging now that detonation has been reduced, and are anxious that we should press on with the aluminium head and fully salt cooled valve. At the same time, in order fully to explore the possibilities of the head, we think it is worth while altering the cylinder pattern so that a larger exhaust Valve can be tried. The least desirable feature of the cylinder at the moment from a car point of view is the rapid rate of pressure rise, although of course we have no means of knowing what effect this would produce in a chassis. Nevertheless, it would give us more confidence if you could demonstrate that you could control this rate of pressure rise by varying the throat between the cylinder and the combustion chamber and the shape of the combustion chamber. The Americans appear to have obtained such remarkable results in controlling the rate of pressure rise on their side valve heads that we ought to be able to do something in this direction. [handwritten] Done [/handwritten] As mentioned, it would be of considerable assistance to us in comparing the single cylinder results with those of the full scale engine if power figures could be taken at a fixed depression of, say, 1 1/2" of mercury at max. revs. full throttle, which is generally speaking the depression at which we have to work the car engines for good snap opening up at low speeds. The suggestion is that if a large capacity receptacle were placed between the cylinder and the carburetter, a reasonably steady depression might be measured and ramming effects reduced. Similarly, a large capacity on the exhaust side might reduce the effect of exhaust ramming. Your suggestion of tapping the pipe between the carburetter and the engine might give the same results, but we think both ought to be tried. [handwritten] Doesn't work [/handwritten] We think it is necessary to have a number of cylinder head castings, and should not be frightened of making pieces if we can facilitate the progress of the job. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||