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).
Note on the Olley report of February 1940, comparing fuel consumption curves and overdrive economy for various cars.
| Identifier | ExFiles\Box 147\5\ scan0162 | |
| Date | 14th May 1940 | |
| To HV. c. Jnr.{Charles L. Jenner} c. Rm{William Robotham - Chief Engineer}/CRS. c. Rm{William Robotham - Chief Engineer}/FD.{Frank Dodd - Bodies} c. Rm{William Robotham - Chief Engineer}/EWS. Rm{William Robotham - Chief Engineer}/RAS.10/RH.{R. Hollingworth}14.5.40. NOTES ON THE OLLEY REPORT OF FEB.18TH. 1940. Attached are curves comparing "short ton miles/U.S.gallon" of our own cars with the average American car figure provided by Olley. The corresponding "constant speed consumption" curves are also drawn since these show what really happens to the petrol. The slope of both curves for 4.B.50 indicates lack of part throttle economy. This is due to richening up to avoid cold weather weakness. Better things are hoped for when the new induction pipes become available. Olley quotes an average figure of 110 cubic ft/ton mile for the American car travelling three up. The following are our figures calculated on the same basis:- Wraith 96 Oldsmobile 105 Bentley V 110 Century Buick 114 Phantom III 114 1938 Minx 74 4.B.50. 119 This appears to be quite a fair method of comparing direct gear performance. We agree with Olley's remarks concerning overdrive economy. On Phantom III overdrive gives 15% better consumption at 30 m.p.h., 11% at 50 and 8% at 70. It is doubtful, however, whether overdrive would mean more than 5% over a long period of running, even if the percentage of town work was small. | ||