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 Bentley cars, related to the bedding-in period of new piston rings.
| Identifier | ExFiles\Box 144\3\ scan0048 | |
| Date | 27th March 1936 | |
| W/K - KC. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}7/KW.27.3.36. Oil Consumption on the Bentley. Many thanks for K/KC/23.3.36. and for the information contained therein. We think one point which is not generally realised is that with the modern cylinder bore finish obtained, particularly after the car has been run to polish up the bores, if new rings are fitted a considerable period must elapse before they become bedded in. It is therefore quite impossible to expect the fitting of new rings to produce an improvement in oil consumption until the car has run 2,000 or 3,000 miles. We appreciate your difficulty in that it is not much good changing a customer's rings and telling him to go on running for this period, in the meantime paying for oil. The solution is to fit rings which will bed themselves in more rapidly, but then we are up against the difficulty of rings which bed in quickly rapidly increasing the gap size. However, we are experimenting in this direction and may be able to offer you some rings with a turned surface but a very hard material before long. We think it would be to our mutual advantage if you would keep us in close touch with any work you are doing on the subject. We attach the daily oil consumption figures of two cars we are at present running endurance tests, from which you will see the length of time taken for the rings to accommodate themselves to the bores. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||