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).
Fuel consumption (M.P.G.) tests and driving techniques to improve economy.
| Identifier | ExFiles\Box 183\M22\ img136 | |
| Date | 28th October 1920 | |
| Contd. -3- Hs{Lord Ernest Hives - Chair}1/LG28.10.20. following M.P.G. 1. Engine running the whole time - throttle open sufficient to maintain a steady car speed at 25 M.P.H. M.P.G. 23.2 2. Car run up to 30 M.P.H. clutch withdrawn and engine stopped until speed dropped to 20 M.P.H. - engine started by car run again up to 30 M.P.H. M.P.G. 33. 3. Throttle set so that when clutch is withdrawn the engine will turn over slowly (200 R.P.M.) The car was then run on the test in the same way as No.2. M.P.G. 30. These tests show that very great improvement can be made by de-clutching and still allowing the engine to run slowly! This is the method of driving which was used on the London to Edinboro' run when 24.5 M.P.G. was obtained over the whole run. The consumptions we have given can only be obtained on a level road. We found that if we ran the car up an incline averaging 1 in 15 at 30 M.P.H. - constant speed, the best consumption was 12. M.P.G. We have also proved that rapid acceleration uses a lot of petrol. It is more economical to accelerate on speed slowly. The most economical speed to run we found was 25 to 30 M.P.H. - anything over 40 M.P.H. the consumption increases rapidly. The results of these tests, we consider, show how essential it is to try and keep mechanical losses throughout the engine and transmission as low as possible. It shows that if the car runs 30 M.P.H. - 1000 engine revs; in one hour, approx. 1 gallon of petrol is used to turn the engine at that speed. Contd. G K BLY{B. W. Bleaney - Bentley Sales} (1918) LTD 20 M 12/19 F.S.A. 17 5389 | ||