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).
Comparing detonation in Hispano and EAC engines.
| Identifier | ExFiles\Box 22\1\ Scan119 | |
| Date | 1st February 1924 | |
| R.R. 403A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. RG.{Mr Rowledge} c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to EY. WGR. Expl. No. X9770 REF: Hs{Lord Ernest Hives - Chair}1/LG26. 2.24. X4214 SECRET. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. Detonation. The Hispano engine which we are running on the test bed has a compression ratio of 4.7 to 1 compared with the EAC. engine in PN{Mr Northey}'s car which has a compression ratio of 4.6 to 1. Comparing the Hispano and the EAC. engines using the same fuel and working at approximately the same B.M.E.P., the EAC. is worse for detonation. The Hispano gains a definite advantage in having two plugs on opposite sides of the combustion chamber. It also gains by having two governed ignitions which can easily be synchronised. If the Hispano engine is run with only one plug firing, the detonations are about equal to the EAC. But with both plugs firing, it is much less. The combustion chamber on the Hispano is smaller than the EAC., firstly, because the bore is 4" compared with 4¼" - also, the diameter of the combustion chamber does not exceed the diameter of the bore. The Hispano people must have had to have overcome a considerable amount of prejudice against having battery ignition only. There is no doubt the combination they have chosen of plug positions and type of ignition, reduces detonation to a minimum. Hs.{Lord Ernest Hives - Chair} | ||