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).
From 'R' to 'EH' comparing fuel consumption between a Delage and a Rolls-Royce vehicle.
| Identifier | ExFiles\Box 21\4\ Scan063 | |
| Date | 15th April 1919 | |
| To EH. from R.{Sir Henry Royce} R2/G15.4.19. X.3056.-RE CONSUMPTION TESTS. X.3500. Many thanks for your very interesting memos re consumption tests on various cars. One would conclude from the Delage that with small cylinders and a high geared car it does not necessarily follow that one will have good consumption. I was surprised, until I saw it, that you could not get more than 20 miles to the gallon with the Delage, when it is possibly to regularly get from 16 to 18 with the big R.R. I see it is a very large, heavy and clumsy chassis. I have every confidence that if the temperature of the R.R. is sufficiently high, and the roads are hard, in an ordinary cross country journey 16 miles to the gallon can be obtained. You will notice that the cylinder capacity per mile is tremendously high with the R.R. compared with the Delage. I hope later we shall be able to investigate still further the various causes which govern consumptions, but it is quite evident that recent poor consumptions are due to poor petrol, combined with an engine which is too cool. The Delage seems to have insufficient radiator for summer, therefore it has the advantage of a fairly hot engine even now. For the T.T. race in 1905/6, I gave them high gear, high compression, slow speed engine, hard tyres, jet control from dash and hot water throttle intentionally, all of which seem good and necessary. The petrol was good and control of water temperature not thought of, or perhaps necessary. R.{Sir Henry Royce} | ||