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).
Report discussing the pros and cons of an overhead camshaft engine project, including a Q&A on power output.
| Identifier | ExFiles\Box 113\5\ scan0196 | |
| Date | 2nd August 1937 | |
| -2- Hml/R.2.8.37. be fundamentally lighter and cheaper to produce, might be expected to give better combustion control and, within the speed ranges possible on a six-cylinder engine, seems to have a good chance of producing an equal performance. However, we agreed with the O.H. camshaft as being a good second string and did not actively oppose the project. The overhead camshaft project was produced 'ab initio' as a completed six-cylinder unit adapted to a Bentley crankcase. The O.H. inlet side valve exhaust as a single cylinder, so that the possibilities of the construction and best proportions could be determined before a multi-cylinder design was started. The single cylinder work shows sufficient promise to encourage the preparation of a multi-cylinder engine, but until this has been run it is quite impossible to say that some very marked and hitherto unforeseen disadvantage may be encountered. With the overhead camshaft engine, on the other hand, we know the worst as we have it in a car on the road. Personally, we strongly disagree with the present tendency to conclude an experiment as soon as we feel that there is no immediate application for the results on production. Before we put the O.H. camshaft engine on one side, we consider that we should have an answer once and for all to the unknowns about overhead camshaft engines so that if ever the subject crops up again, a tabulated list of the pros and cons will be available, to prevent a repetition of previous experimental work and design mistakes. The queries relating to this unit when designed, and the answers so far obtained are as follows:- QUESTION (1) Can additional power be obtained from this construction? (2) Can this power be utilised on the road ? ANSWER. Yes, a very marked increase(25%) in top power, and possibly in low speed power to a small extent, but the best camshaft has not yet been tried. (Curve S.20. attached) A lot of this power is dissipated in the existing exhaust system, but no work has been done to see if this can be reduced, and very probably it will be reduced with the proper camshaft. Even with | ||