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).
Piston oil consumption improvements and the potential contributing factors.
| Identifier | ExFiles\Box 16\1\ Scan114 | |
| Date | 8th July 1930 | |
| Btn-3 July 8, 1930. To: Mr. Beaver From: Mr. Burton Cc- Mr. Soutter Mr. Olley PISTONS Reference your memo of July 2nd, I have not written Mr. Olley on this subject since April 24th last when I sent along for his signature standardization sheet No. 134. The reason for this is that my information on this subject is not complete and I am not yet able to tell him anything definite. We are of course aware that an improvement in oil consumption is obtained by the use of P.C. Rings, but according to test records this is nothing beyond what might be expected. Comparing early MR with PR records, the oil consumption appears to have improved from an average of 800 m.p.g. to 1000 m.p.g. - just a 25% improvement. - This we cannot consider wonderful. Further we do not know whether to ascribe this improvement to one or other of the three features - (a) Use of Perfect Circle Rings. (b) Use of Bleeder Holes behind the rings. (c) Correct fitting of the top rings. On a recent visit to New York I was discussing this question with Mr. Ainsworth, and suggested to him that it was not so much the Perfect Circle Ring that gave us the improvement but rather the introduction of a row of 16 holes in the lower groove which eliminated the pumping action of the rings, and asked him to try on his own car the effect of just drilling these holes. Although I have reverted to this matter several times since, I have not yet had a report that this has been done or its effect on oil consumption. I think it is most essential that we should determine this point as this gives us a possibility of being able to cure overoiling merely by drilling the pistons, thus eliminating the necessity of fitting new pistons and also the 12 hours "running in". - continued - | ||