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).
Fuel self-ignition tests, comparing Shell Mex spirit and Benzol, and the effects of water and air temperature.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan217 | |
| Date | 8th June 1926 guessed | |
| contd :- -4- Under these conditions Shell Mex spirit would ignite up to 28 seconds of slow running but Benzol would not ignite after 18 seconds. This proves that the higher the self ignition temperature of the fuel the less liable it is to give trouble in this respect. It would be imagined that anything which tended to raise the suction temperature of the charge would make the trouble more evident. Therefore the effect of water and air temperature was investigated. WATER TEMPERATURE. Water temperatures between 20°C and 80°C made very little difference and less than two seconds resulted in the slow running period mentioned before. We have further taken the water outlet from both ends of the cylinder with no different results. AIR TEMPERATURE. For the previous tests the intake air temperature was 18 to 19°C but for this test it was raised to 62°C by an electric heater. This resulted in being able to obtain self ignition on switching off after 34 secs. slow running against 28 secs. with the air at the lower temperature. In other words, the valve had six seconds to cool. GENERAL CONCLUSIONS. The conclusions we draw from the results of our tests are that when self ignition takes place it is due to the com- pressed charge picking up heat from the hot exhaust valve. low rate of revolution in conjunction with the hot contd :- | ||