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).
Comparison of engine performance with different carburettor, induction, and valve configurations.
| Identifier | ExFiles\Box 5a\5\ 05-page216 | |
| Date | 1st November 1922 | |
| HS{Lord Ernest Hives - Chair}/AGL/AR.11.22. Contd. -2- very low depression at low speeds renders it very poor for "pick up" and acceleration. We have however, enlarged the chokes and air ports of the Std. 20 HP. carburetter so that it gives only about 4 HP. less than the Zenith when either are used in the Standard position on the engine. Referring to the curves on V.737. we obtain the following information :- Curve "A" represents the power output with large valves, large induction pipe, Zenith carburetter attached to this pipe and thereby eliminating the passage through the cylinder block. 5.25/1 compression ratio and 110° camshaft. Max. power 85 B.H.P. Curve "B" is the same with the exception that a standard induction pipe is used and the Zenith carburetter passes its mixture through the passage in the cylinder block. 79 B.H.P. is given with this arrangement therefore a loss of 6 B.H.P. (or 7%) can be attributed to restriction in passing through the cylinder block passage and the smaller induction pipe. The passage through the cylinder block for this test is 30% larger than standard. Curve "D" represents the standard China engine with the standard valves and ports, 110° camshaft but having a compression ratio of 5.25/1. Larger induction pipe and Zenith carburetter. The power peaks at 74 B.H.P. at 2900 R.P.M. | ||