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 | WestWitteringFiles\L\Jan1924-March1924\ Scan62 | |
| Date | 12th July 1923 | |
| R.R. 403A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} H-S & EAC rep Detonation ORIGINAL Expl. No. X9770 x4214 REF: Hsl/1026.2.34. EXPERIMENTAL REPORT. SECRET. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. & HISPANO To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. RO.{C. C. Rose - Export Manager} c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} WOR.{Arthur Wormald - General Works Manager} 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 4 1/2" - 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} | ||