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 and modifying the India IV engine's compression ratio to resolve pre-ignition issues.
| Identifier | ExFiles\Box 5a\5\ 05-page074 | |
| Date | 28th March 1929 | |
| Ha/ACL1/LG28.3.29. INDIA IV - ENGINE COMPRESSION RATIO AND PRE-IGNITION. The original India IV. cyl. head gave a compression ratio of 3.6/1 and with this we experienced considerable trouble both on the test bed and road through pre-ignition. On the test bed we could not run for a minute on full load with the standard K.L.G. 3-point (K.1.) plugs without pre-igniting. Substituting aero plugs pxx - Lodge A.40. we were able to run at full load but even these gave trouble on the road no doubt due to the higher intake temperature under the bonnet. We modified the original head by machining the sides of the combustion chamber to give a compression ratio of 5.1/1 and effected a considerable improvement in freedom from pre-ignition although we were not entirely free from this on the test bed. On the road however there still exists signs of preignition. The maximum power given with the 5.1/1 head is 62.2 HP. at 3000 r.p.m. which is 13 HP. more than given by the average 20 HP. production engine. Appended are curves giving a comparison of the India IV. with 5.1/1 comp: ratio and the standard production 20 HP. Looking into the question of preignition we carried out some tests with the high compression head on the test bed by using an additional water pump (Phantom) to circulate one end of the head and the outlet at the other. could :- | ||