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).
Comparing engine overheating and cooling efficiency with a Hispano Suiza engine.
| Identifier | WestWitteringFiles\L\2April1924-June1924\ Scan63 | |
| Date | 14th May 1925 | |
| R.R. 493A (50M) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Ra/LG14.5.25. associated with R.R. cars, is low compression. The Hispano Suiza, on the other hand, is smaller, has overhead valves and high compression. The effect of the two different designs on overheating is as follows :- | | B.Th.U. Heat units to cooling water. | Brake H.P. developed. | |---|---|---| | 1000 R.P.M. | | | | Hispano Suiza, | 2000 | 54.5. | | Standard Rolls-Royce. | 2678 | 46 | That is, the Rolls-Royce engine imparts 33.9% more heat to the cooling water while transmitting 15.6% less power to the road wheels. It is therefore clear that to compete with the Hispano Suiza, which has been mentioned by way of comparison when complaining of boiling troubles, we have got to ensure that for factor (b) our cooling system is at least 33.9% more efficient than that of the Hispano. The design of the engine is fixed, as is also the limit of permissible compression ratio, so further advance in section (a) is impossible. Now there is no royal method of improving the efficiency of a radiator system. There are certain alterations which can be effected in the system which will produce a slight increase in efficiency at the expense of added complication and reduced reliability. Two of these most widely known are - steam cooling, and a radiator system under pressure. These have been carefully considered by R.{Sir Henry Royce} and the Expl: Dept: and rejected. No other promising modification appears contd :- | ||