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).
Use and specifications of Bensfort pistons, including dimensions and compression ratios.
| Identifier | ExFiles\Box 86\2\ scan0006 | |
| Date | 3rd March 1933 | |
| E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X236. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}6/KT.3.3.33. BENSFORT PISTONS. On all our test bed work we have been using standard pistons. On the car running in France, however, we find that the pistons had .030" additionally on the top of the crown, being made to E.56610. This, therefore, answers your query with regard to the running of pistons flush with the top of the block. We still think, however, that if we have two pistons so nearly to the same dimensions as E.56610 and E.57122, there will be a definite chance of confusion occurring, and also we have noted no ill effects when running the pistons .030" below the top of the block with the turbulent head. From actual power output and freedom from detonation, therefore, we do not mind what pistons are used so long as the head is adjusted to give a compression ratio of 6.3 with a copper and asbestos gasket. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||