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).
Page discussing engine pressure cooling systems, steam pockets, and a comparison with Ethylene Glycol.
| Identifier | ExFiles\Box 149a\3\ scan0234 | |
| Date | 16th November 1938 | |
| -3- (7) With pressure cooling it is essential to have a well-designed water pump and water passages, capable of keeping up flow with inlet temperatures of 90 - 95°C, and also the coring of the cylinder head must be watched to avoid steam pockets - in this connection it is very desirable to work with a fairly high cylinder block coolant pressure (say 10 - 15 lbs/sq. inch in excess of general cooling system pressure). It must be stressed that the only real trouble experienced by the aero people (attributable to pressure cooling) has been due to steam pocketting and has occurred when running at approx. zero pressure at approx. 100°C - when functionning under limit conditions of 15 lbs/sq. inch and 121°C this steam pocket trouble does not occur. In this connection, our engine thermostats would greatly help matters. In case of either pressure cooling or Ethylene Glycol, the higher coolant temperature materially increases detonation - glycol being considerably worse than pressure cooling in this respect owing to the high metal temperature already mentioned. | ||