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).
Carburation and petrol consumption, illustrated with a graph of typical curves for a 4-stroke petrol engine.
| Identifier | ExFiles\Box 178\1\ img056 | |
| Date | 21th November 1925 | |
| - 9 - EXPERIMENTAL REPORT. EXPL. No. REF. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG21.11.25. when these are fitted, instead of making a gradual stop with the throttle closed. Again, the average speed of the car almost always is increased when driving with front wheel brakes. This in itself gives an adequate reason for increased petrol cons: CARBURATION. It is not generally realised that if a carb. is set for minimum petrol consumption to give max. power, the car will still not be running under its most economical conditions. A small amount of power must be sacrificed if economy is of primary importance. A much more potent factor, however, is that the mixture can be very much over-rich without any falling off in power and performance. This is quite clearly shown in Graph IV. the GRAPH IV. GRAPH IV Typical Curves for an efficient 4-stroke Petrol Engine. (contd). Graph Y-Axis Label: B.H.P. & PERCENTAGE THERMAL EFFICY. AT 1000 R.P.M. Graph X-Axis Label: PETROL PER LB. OF DRY AIR. Graph Labels: EFFICIENCY, B.H.P., CHEMICALLY PERFECT MIXTURE, MAXIMUM POWER. | ||