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).
Test report on engine pre-ignition, liner temperatures, and the effects of varying oil pressure.
| Identifier | WestWitteringFiles\P\October1926-November1926\ Scan062 | |
| Date | 18th October 1926 guessed | |
| contd :- -4- without further drop in power. The pre-ignition was not as severe as we have experienced and gave no popping back in the carburetter. With pre-ignition the top of the liner temperature rapidly increased to 132.5°C where it remained constant, the aluminium cyl. temperature at the same spot was 106°C. Pre-ignition did not seem to appreciably alter the temperature of the lower parts of the bore. During some of these tests it was thought that a slight variation of the cylinder skirt temperature was observed when the oil pressure was varied. Consequently a test was made in which the oil pressure was reduced and although the actual oil flow through the bearings was not measured at the time we estimated from previous figures taken on this engine that the flow was reduced by roughly 70%. The normal oil flow on this engine is considerably higher than on the average engine due to the worn state of the bearings after a large number of hours this particular crankcase unit has run on the test bench. At 2000 r.p.m. the skirt part of the liner was approximately 10°C higher with this reduced flow. The temperature of oil admitted to the bearings was kept constant at 60°C in each case by a cooler. The higher parts of the liner were not affected to any appreciable extent. As the exact oilflow was not known but only estimated we intend to repeat this at the first opportunity to see if the temperature is likely to increase much with well fitting bearings. contd :- | ||