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).
Trial of a lower compression ratio on S.S. cars to improve engine smoothness.
| Identifier | WestWitteringFiles\T\2July1929-December1929\ Scan013 | |
| Date | 17th July 1929 | |
| SECRET. ORIGINAL To R.{Sir Henry Royce} from C. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} C. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} C. to By.{R.W. Bailey - Chief Engineer} S.S. CARS. ----------- x7770 x490. We have tried one of the Expl. cars with the compression ratio reduced to the same as the standard Phantom (S.S. at present is 4.6 to 1, Phantom 4.25 to 1.) The effect of lowering the compression is to make the engine smoother and more silent. There is however a slight loss in performance. It must be accepted that whatever improvements we can make, the lower compression car will always be smoother. We attach herewith print shewing how the head was altered to obtain the lower ratio with the existing casting. We do not find any disadvantage from machining away the lip in the combustion chamber. This is more convenient than alternative heads, as no other parts have to be altered. We recommend that we allow the lower compression to be used where max. performance is not required. Hs.{Lord Ernest Hives - Chair} | ||