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).
Design analysis of a Chevrolet-style cylinder head and a High Power Main Engine, discussing combustion, valving, and valve gear.
| Identifier | ExFiles\Box 134\2\ scan0062 | |
| Date | 15th July 1935 | |
| -2- A mathematical investigation was carried out with this plug position after the style of Chevrolet's to see whether or not this combustion chamber had any potential qualities of smoothness, and the curves shown on Fig.l resulted. Due to the very approximate nature of the calculation, these curves should not be regarded as dead accurate, but they are probably within 10%. From an inspection of other curves, it would appear that the ideal is to keep the curve of % volume increase against % flame travel within the straight line area, and it would therefore appear that the high power head should run fairly smoothly. An attempt was made to calculate the curves for the other plug position, but this was abandoned due to the complexity of the calculation. The Chevrolet cylinder head, which was designed with these curves as a basis, is shown in Fig.II as opposed to the High Power head. High Power Main Engine. In the two memos. Hs{Lord Ernest Hives - Chair}/Smth.20/KW.15.7.35, and Hs{Lord Ernest Hives - Chair}/Smth.14/KW.11.5.35, we have a fairly comprehensive survey of the position of this head as regards the formation of a main engine. As is pointed out, we have better valving than the Bentley by about 60%, and this does not represent the limit, as valve sizes in this head are probably limited more by the inertia and mechanical strength of the valve gear than by the size of valve it is possible to get in. Even with the existing valve sizes, the chief difficulty is valve gear. If a single inlet valve is used, we have a heavy valve, with what may prove excessive valve loading, and also a tendency to excessive high speed detonation. With two inlet valves we have the alternatives of two push rods or a forked rocker. | ||