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).
Blueprints for E.82168 and E.82455 compression ratio heads and the difficulties of achieving higher compression ratios.
| Identifier | ExFiles\Box 14\3\ Scan067 | |
| Date | 22th September 1931 | |
| 87050. To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}4/MJ.22.9.31. PII Herewith blue prints of E.82168 and E.82455, the 5/1 and 5¼/1 compression ratio heads respectively as produced by the D.O. We think that you will agree that these heads are not ideal but you no doubt appreciate the difficulties of getting the higher compression ratio without a complete redesign of the head. We have never had a power curve of either of these heads although the 5/1 head was put on to 25-EX. car at the last moment before it went to France. All the high compression heads we have in the Experimental Dept., and of which we have given you power curves, have been the standard head with the maximum permissable amount shaved off the base. In certain circumstances we have been able to get 4.9/1 but naturally the head is not a practical production proposition in this condition. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||