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 petrol consumption of a Chevrolet and a 30 HP Rolls Royce.
| Identifier | ExFiles\Box 147\5\ scan0116 | |
| Date | 26th November 1936 | |
| E.{Mr Elliott - Chief Engineer} from Rm{William Robotham - Chief Engineer}/F.{Mr Friese} Dodd. c. to Hs.{Lord Ernest Hives - Chair} c. to By.{R.W. Bailey - Chief Engineer} CHEVROLET PETROL CONSUMPTION. We have taken petrol consumption tests on the Chevrolet using a 30 H.P. R.R. as a check car. The revs/mile of the two cars is almost identical; below is a specification of the two cars:- | | Weight cwts.qrs.lbs. | Engine Capacity. | Axle Ratio. | Tyre Size. | Engine RPM. at 60 MPH. | |---|---|---|---|---|---| | RR. 30 H.P. | 38. 2. 7. | 4,257ccs. | 4.55:1 | 6 x 19 | 3,040 | | Chevrolet 27 H.P. | 28. 3. 21. | 3,358 " | 4.11:1 | 6 x 16 | 3,056 | The Chevrolet is fitted with a suction operated ignition advance which gives an additional 10° advance over the automatic at part throttle openings. We have checked the petrol consumption at half throttle, with and without the suction advance, and find we obtain 21 m.p.g. and 19 m.p.g. respectively, a gain of 2 m.p.g. using the suction advance. When using full throttle, i.e., driving hard on a high average speed run the difference is half as much - 1 m.p.g. A petrol consumption was also taken of the 30 H.P. Rolls as a check, and below are the comparisons:-:- | | Half Throttle with Suction adv. | Half Throttle No suction adv. | Full Throttle with suction adv. | Full Throttle No suction adv. | |---|---|---|---|---| | RR. 30 H.P. Std.Ignition. | 18.16 mpg. | 18.16 mpg. | 14.03 mpg. | 13.37 mpg. | | Chevrolet 27 HP. | 21. " | 18.92 " | 18. " | 16.9 " | The above tests were taken with the cars at their respective weights. | ||