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).
Testing a reduced compression ratio in an S.S. car engine for smoother operation.
| Identifier | ExFiles\Box 19\7\ Scan145 | |
| Date | 17th July 1929 | |
| SECRET. X790 R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}5/MJ17.7.29. X7770 X790. S.S. CARS. 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 walways 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 th 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} | ||