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 comparing standard and 'L' shaped piston rings, with a proposal for a new scraper design.
| Identifier | ExFiles\Box 71\4\ scan0085 | |
| Date | 25th March 1925 | |
| EXPERIMENTAL REPORT. -2- Expl. No. REF. Hsl/LG25.3.25. If we place an EAC. cylinder block on the bench and fit to one bore a piston fitted with standard rings and the after amply lubricating the bore we slide the piston up and down in it, it is easy to observe that with the standard rings the oil is scraped in either direction equally. If we change the rings for 'L' shaped ones, no oil can then be observed to be scraped forward, but it is all scraped backwards. We have run a car fitted with an EAC. engine and 'L' shaped piston rings, and the oil consumption averaged nearly 1000 m.p.g. This same car with standard rings xx averaged 410 m.p.g. If ever we did at any time wish to use a very effective scraper, we suggest it might be made somewhat as follows :- There would be a steel expanded ring in order to maintain an uneven loading on the scraper. As regards the excess oil on the rockers causing over-oiling. This makes itself apparent if the engine is run light. The high suction drawing the oil down the inlet valve guides. Comparative tests in France show that with the maximum amount of oil being fed to the rockers, the oil consumption of the car was 340 m.p.g., when the oil to the rockers was reduced, the oil consumption increased to 385 m.p.g. Most of this running, of course would be under full throttle conditions. contd :- | ||