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).
Preignition issues, comparing water cooling effectiveness in aluminium and standard cast iron cylinder heads.
| Identifier | ExFiles\Box 5a\5\ 05-page075 | |
| Date | 28th March 1929 guessed | |
| contd :- -2- The standard water pump admitting water to the cyl. blocks was retained. It was thought that if the trouble was due to hot spots at some part of the head, or inadequate cooling of the plugs, the above scheme should make appreciable difference. However the results were not satisfactory and preignition still persisted. It will be remembered that during some tests carried out on the old cast iron 30 HP. with the large valves we employed a compression ratio of 6/1 and in spite of the miniature K.L.G. plugs which we used with this head we had no trouble from preignition. In one case we developed 92 B.HP. at 3200 r.p.m. without trouble. We therefore obtained some sections of both the India IV aluminium and std. cast iron heads. Looking at the alum. head section we found there was very little water space round the spark plug boss - actually it was difficult to thread a piece of .062 dia. wire through the passage. This is much less than shown on the drg. K.54853. Comparing this with the cast iron head we find there is provision for more adequate water circulation round the plug bosses on the latter as shown on our appended sketches. We have not yet any definite experimental proof that the alum. head is any worse with regard to hot spots than the cast iron head but it is interesting to remember the preignition trouble was not manifest on the old engine during our high comp. experiments. contd :- | ||