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).
Analysis of liner and cylinder temperatures comparing aluminium and cast iron cylinders under different operating conditions.
| Identifier | WestWitteringFiles\P\October1926-November1926\ Scan061 | |
| Date | 18th October 1926 guessed | |
| contd :- -3- The appended curves are the results and shew the temperature of the top of the liner and cylinder wall for the different speeds also the B.M.E.P. maximum developed at the time. From these curves we see that the liner temperature is in excess of the aluminium cylinder temperature by 21°C at a speed of 2500 r.p.m. - the highest normal temperature recorded at this position being 124.4°C or 44°C higher than previously obtained for the standard cast iron cylinders using 4.1 to 1 compression ratio. The compression ratio used during these tests was 4.69 to 1 and the B.M.E.P. developed was 75 lbs/sq.in. at this speed. We notice that the average water temperature was lower when the test on the standard cast iron cylinders was made therefore 80°C for this is probably rather a low figure. Another diagram shews how the temperature varies at different parts of the cylinder, the hottest spot recorded being where aluminium skirt finishes and the coolest at the bottom of the jacketed part. The observed readings shewn on the diagram are connected by straight lines for the sake of clearness but we have no proof that temperatures at intermediate points lie on these lines. It was imagined that conditions of pre-ignition would appreciably increase the temperatures consequently the engine was run hard with two Lodge three-point sparking plugs in this cylinder until conditions of pre-ignition were evident by a drop in the average B.M.E.P. of about 9 lbs/sq.in. Furthermore, the two plugs in this cylinder could be 'shorted' contd :- | ||