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).
Modifications to raise the compression ratio of a 40/50 engine.
| Identifier | ExFiles\Box 14\3\ Scan059 | |
| Date | 10th January 1931 | |
| To RHC.{R. H. Coverley - Production Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X7050 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/MJ.10.1.31. RAISED COMPRESSION RATIO. 40/50. The present 40/50 compression ratio is 4.6S. We want to raise it to approximately 4.9. To do this we must drop the turbulent head 1.150. We shew a section from the cylinder head which indicates the only points where the metal is likely to be too thin. However, at these points the metal has only to be water tight and it should be possible to observe on the casting that it is well up to the drawing size of 250. We should like you to take .125 off the bottom of the cylinder head of the test bed unit 3.S.7. We should also like a gasket made of aluminium .025 thick which will enable us to gain a little more. These two modifications should practically give us what we want. If it is found possible to take more than .125 for the cylinder head it would suit us up to .160. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||