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).
Car engine cooling performance and seeking advice on remedying related issues.
| Identifier | ExFiles\Box 149a\3\ scan0169 | |
| Date | 16th June 1936 | |
| -2- If T = temperature of water in top tank (°C.) and ta = atmospheric temperature (°C.), then critical air temperature; i.e., air temperature at which car will just boil under given conditions, is 100 - T + ta. Some of the conditions used for comparison are probably more arduous than would normally be met with in service; i.e., 30 or 40 M.P.H. full throttle in top gear, but in any case they can be used as a standard of the car's cooling. The high speed full throttle figure is of course an absolute measure of the adequacy of the car's cooling system at high speed, since it is a condition which definitely will be met in service. The Bentley and the 20/25 HP. cars, which we know are more than adequately cooled in service, have minimum critical air temperatures (i.e. under the worst of our test conditions) of 48°C. and 53°C. respectively. The Phantom III Car, however, as can be seen from the attached sheet, is very much worse off. We are hoping materially to improve the low speed cooling by a more effective fan, but are somewhat chary of fitting a deeper matrix because of excessive under-bonnet temperatures causing petrol boiling, with which we are already somewhat in trouble. We should very much like to receive information on the following points from you, as well as your advice on how we can remedy these troubles :- (1) How do you define or measure the cooling of your cars ? (2) What is your standard of adequate cooling for a car ? We consider that a minimum critical air temperature of 40°C. is desirable. (3) On a car of the Cadillac 16 type, what is the value of the cowling in front of the matrix from the point of view of increasing cooling ? (4) What is the value of cowling the fan behind the matrix with the same object in view ? | ||