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).
Compression ratio tests and findings on test bed engines.
| Identifier | ExFiles\Box 19\7\ Scan146 | |
| Date | 9th September 1932 | |
| X790 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}7/AD.9.9.32. JAPAN 3. COMPRESSION RATIO X5050 All the cylinder heads we have had on our test bed engines have been to drawing E.57126. The volume of this cylinder head is 143.5 cc, the swept volume of each cylinder is 744 cc. and the volume of the gasket is 7.44 cc., this gives a comp. ratio of 5.92/1. In order to get a comp. ratio of 5.5/1 we fit 3 gaskets under the cylinder head which give the required result. The plugs cannot be considered to be very bad for preignition because we were able to run with K.L.G. K.1 type for 10 hours with 5.9 comp. ratio developing 100 H.P. without any very serious preignition. On the whole this engine appears to be worse than the 25 HP. for detonation and we are inclined to agree that 5.5/1 will be about the limit of the comp. ratio from our present knowledge. Naturally, this detonation may have been due to portions of the head being ineffectively water cooled and therefore our views are susceptible to modification. The water passages between the head and block require reducing in number as on Peregrine. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||