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).
Page illustrating the thermal efficiency curve of a 4-stroke petrol engine and discussing the performance of the Phantom model.
| Identifier | ExFiles\Box 178\1\ img053 | |
| Date | 21th November 1925 | |
| - 6 - EXPERIMENTAL REPORT. EXPL. No. REF. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}1/LG21.11.25. The graph below illustrates this:- GRAPH 1. GRAPH I THERMAL EFFICIENCY 4%, 8%, 12%, 16%, 20%, 24% PERCENTAGE FULL LOAD ON ENGINE 0, 20%, 40%, 60%, 80%, 100% Typical curve for efficiency 4-stroke petrol engine. On the Phantom, 9.5 HP. is required to propel the car on the level at 30 m.p.h. The engine is capable of developing 60 HP. at this speed. It is therefore only working at 16% full load. Under these conditions every B.HP. developed takes as much petrol as 2 1/2 HP. generated under full load conditions. Owing to these facts every car has a speed usually about 15 m.p.h. at which it will give the greatest m.p.g. (contd). | ||