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).
Analysis comparing engine performance curves based on variations in camshafts, valves, and compression ratios.
| Identifier | ExFiles\Box 5a\5\ 05-page217 | |
| Date | 1st November 1929 | |
| -3- Compare this with curve 'A' and the difference of 11 B.H.P. (or 15%) represents the combined gain due to the larger valves and 116° camshaft. We have not yet separated the effects of the 116° camshaft and the large valves but are of the opinion that perhaps better all round results would be obtained with the 110° camshaft (Std.) We know that increasing the angle between the cams usually tends to improve the power at high speeds, but at the same time gives a reduction at low speeds. The only difference in specification between curves 'C' and 'D' is that 'C' has the std. compression ratio of 4.75 to 1. If we look at curves 'B' and 'D' we find that 'D', although giving 5 HP. less than the former has the advantage below 2500 R.P.M. There are several differences in the specification, viz. 'B' has larger valves and higher compression ratio, while to effect this the other has a low depression carburetter but, although a strict comparison cannot be drawn, we think the chief factor resulting in the inferior power at low speeds is due to the camshaft. We are now carrying out a test to compare the 110° and 116° camshafts. Turning now to print V.734 we give a comparison of the standard carburetter with a carburetter in which we | ||