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).
Tests and observations on a pressure cooling system, including performance at Brooklands and proposed modifications.
| Identifier | ExFiles\Box 131\1\ scan0311 | |
| Date | 1st September 1937 | |
| -3- Note It was noticed throughout the tests at Brooklands and in journeys to and fro from the track, that the pressure at any given moment did not correspond to the pressure which is obtained from steam tables, corresponding to the temperature of the coolant. No satisfactory explanation of this has yet been found, it is thought that it may in part be due to local hot spots in the cylinder heads causing correspondingly higher temperatures and pressures. (3) The pressure cooling system gave no trouble throughout the tests except that the drain cock on the water pump worked to the open position during the first few laps at Brooklands, this is now being fitted with a locking device however. It is necessary to make a sound joint at the filler cap and a different material washer will be tried for this purpose. The engine was not fitted with an oil cooler and one of the normal type would be useless since under extreme conditions the water would not appreciably cool the oil, in fact might even tend to heat it. The oil pressure after a number of high speed laps at Brooklands was of the order of 17 - 18 lbs/sq.in. The engine has since been stripped and the cylinder blocks are remarkable for being almost entirely free from corrosion- this is probably in part due to the Izal corrosion inhibitor added to the coolant. The radiator valve was tested after the above tests and its blow off pressure had not varied from 12 lbs. sq.in. - presumably it had not been left long enough in a closed position to stick to its seating. A new type of seating (Neoprene, made by the Avon Rubber Co.) has been fitted in place of the old type (made by British Goodrich Co.) but we are also trying a simple ball valve. SUMMARY (1) There seem to be no disadvantages about the pressure cooled system as fitted to J9-EX. car, other than the difficulty of obtaining a satisfactory steam valve, and the chances of doing this are good. (2) The advantages to be gained, using the 6lbs/sq.in. valve as will be fitted to J9-EX. for France are (a) Reduction in weight and cost. (b) Adequate cooling under all conditions. (c) Decreased corrosion. (d) Lower under-bonnet temperatures owing to use of thinner radiator matrix. (e) Freedom from water loss under normal running conditions. continued | ||