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).
Oil consumption on the 25/30 HP chassis, piston performance, and testing.
| Identifier | ExFiles\Box 144\3\ scan0087 | |
| Date | 14th July 1936 | |
| To Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} c.c. to E.{Mr Elliott - Chief Engineer} c.c. to Hy.{Tom Haldenby - Plant Engineer} c.c. to H.{Arthur M. Hanbury - Head Complaints} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}19/KW.14.7.36. Oil Consumption on 25/30 HP. Chassis. There are one or two points in connection with this difficulty which have not been mentioned. (1) It is hardly correct to say that the 10,000 miles test shows that the early oil consumption was very bad. On the contrary, the early oil consumption on both big bore 25/30 units fitted to 22-G-V was better than either of the previous small bore units which have recently been run in France. The attached chart demonstrates that this is the case. As a matter of fact, though no Standardisation Sheet has as yet been started for the 25/30 pistons in view of the fact that no set has yet completed 15,000 miles' running in France, on the results obtained so far we should have no justification for refraining from circulating a sheet on the score of poor oil consumption. These tests indicate that we finally settle down to a better oil consumption than we have recently been getting on 20/25's, and it might be argued that the modification to the ring arrangement had produced this result. (2) Piston ring stops were not lightly discarded. We have had a good deal of trouble with them in the past when we pushed the speed of our engines up, and we can show you several samples of piston where the stops have broken off and caused a major failure. The Works have always told us that stops are expensive, and we believe we are correct in saying that only one other manufacturer in the world uses them to-day. (3) Answering your question as to what pistons were fitted to your own and wor{Arthur Wormald - General Works Manager}'s cars. Aerolite pistons were used on all the advance 25/30's. The drawings for the R.R. 25/30 pistons reached the Experimental Dept. on the 1st November 1935, and dies had to be made. The first set of pistons was on test the second week in February 1936. The car started its 15,000 miles test in the second week in March, and the first chassis was on test a fortnight later. | ||