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).
Page discussing tests on compression ratios, pistons, and sparking plugs.
| Identifier | ExFiles\Box 43\1\ Scan093 | |
| Date | 1st August 1925 | |
| R.R. 493a (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -7- Expl. No. REF. HS{Lord Ernest Hives - Chair}/TAG/LG26. 8.25. difference either way, so that 50/50 was used for all the tests recorded on this report. K.L.G. E.12 sparking plugs were used and gave no trouble. Castrol oil was used. Standard pistons. The compression ratio was checked on several cylinders with standard pistons taken from stock (production), which are supposed to give 5.3 to 1 ratio. We did not find one cylinder or piston which gave the nominal 5.3 to 1 compression ratio, in fact, in one case the ratio was 5.17 to 1 but with the same piston in another cylinder the ratio was 5.27 to 1 and this xxxx figure was the average of those tested i.e., omitting the 5.17 to 1 case. The limits allowed in machining the combustion chamber of the cylinders are rather generous and these would cause the differences (coupled with the probable variation in the seating of the valves) obtained in the compression ratio figures of which 5.27 to 1 is the average. Appended are the theoretical findings on the foregoing tests. HS{Lord Ernest Hives - Chair}/TAG. | ||