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).
Report comparing the engine performance, gear ratios, and fuel consumption of a Marmon car to the standard 40/50 chassis.
| Identifier | ExFiles\Box 180\M4\M4.1\ img006 | |
| Date | 2nd February 1921 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to B. c. to Da.{Bernard Day - Chassis Design} c. to SY. c. to KP. ORIGINAL E.F.C. X.1692 RE. MARMON CAR. Attached herewith is a report on the above Car. It will be seen that the power of this engine is very good. The engine is approx: 25% less capacity than our 40/50 chassis and the horse power, except at low speeds, is approximately the same. Owing to the difference in gear ratio the HP. at given car speeds is higher on the Marmon than on our standard Car. The compression ratio on this engine is approx: the same as our high compression Cars 4.2 to 1. The compression by gauge is 77 lbs. compared with 67 lbs. on our Cars, which shows that the cylinders fill up much better. The ratios of the Gears are also interesting. It will be noticed that there is a very big step between the second speed and the first, which enables them to have a very low first speed. In driving the Car, one cannot notice any very great difficulty in changing gear up. When climbing a hill which necessitates changing down to 1st. speed, the Car slows down so quickly when the clutch is disengaged that a big step between 2nd. and 1st. is not very difficult. The consumption given in this report was taken with the Car running at a constant speed. On the run from West WitteringHenry Royce's home town to Derby, we averaged 12 miles to the gallon with this Car. RECEIVED Hs.{Lord Ernest Hives - Chair} | ||