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).
Engine testing to address piston knock by adjusting oil pressure and piston design.
| Identifier | ExFiles\Box 35\2\ scan 154 | |
| Date | 17th October 1919 | |
| H.H. 235a (500 T) (S.D. 408. 28-4-17.) Em. 2/156/13. Contd. -2- EH5/LG17.10.19. plunger more effective, it would give us more oil at a time when the engine badly needs it. Quite apart from piston knocks we had come to the conclusion that the best way to give our engine more oil is to increase the oil pressure considerably. We cannot see that there will be any disadvantage in increased oil pressure. We have made a test with a piston with an oil plunger, we have had a piston knocking, and by screwing up the relief valve choc-a-bloc we have cured the knock; by releasing the valve the knock has come on again, and we have found that we can play about with the knock in this way and it was surprising that there was very little memory, immediately we lowered the pressure the knock would come on. We have tried the plunger in various positions on the non-pressure side i.e. varying the height of it relative to the gudgeon pin. In order to try it high up we have raised the rings. The tests shew, however, very little difference between it being level with the gudgeon pin and as high up as we can get it. If anything, we should say it is best high up but we have so far not been able to trace any distinct difference. Piston with split on the non-pressure side. A set of these pistons are running on a car. They have run for 450 miles. This set we are running are excellent as regards absence of knocks. We have left the car outside all night and find that when it is CONTD. | ||