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).
Improving engine cooling performance by modifying radiator tubes and assessing temperature changes.
| Identifier | ExFiles\Box 15\1\ Scan381 | |
| Date | 24th September 1930 | |
| -5- He/Gp.1/JAL.24.9.30.Contd. It would seem reasonable that when we use tubes that are not expanded at the ends, the thickness might be slightly reduced. A reduction of .002 in the thickness of the material of the 5t/7 m.m. tube increases the cooling surface available for a given frontal area by 4% approximately. TEMPERATURE OF THE ENGINE. The rise in temperature of the air across the radiator at 30 M.P.H. is about 10-12°C. If we increase our radiator efficiency 25% the temperature of the air entering the bonnet will only rise 3°C. The temperature of the water in the system, however, will fall over 10°C. Since the temperature of everything on the engine, except the exhaust, is largely controlled by the water temperature it will appear that the projected radiator will actually make conditions easier for the fuel system etc. The exhaust manifold being at 500°C. can hardly be affected much by a 3° rise in temperature of the air cooling it. CONCLUSIONS. We shall have the 6 m.m. square tube radiator on test next week. If it fulfils our expectations it should make more difference than fitting the louvred bonnet does to the standard car, i.e. it should raise the critical atmospheric temperature at which the car will overheat by about 10°C. From all the information we have so far obtained it appears that as long as we do not have less than 40% direct cooling our radiator efficiency will increase roughly in proportion to the surface exposed to the air within the limits | ||