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).
Explaining the general principles of heat generation and loss in a petrol engine, using the Silver Ghost as an example.
| Identifier | ExFiles\Box 178\1\ img017 | |
| Date | 15th February 1926 guessed | |
| (1) GENERAL PRINCIPLES INVOLVED. (a) Heat generating capacity of power unit. An automobile petrol engine is a machine for converting heat units as supplied by the petrol into useful work. However efficiently it is designed, it is unable to turn to useful account more than one quarter of the heat supplied by the fuel. Even this is a much better performance than that of a steam engine, however. The remaining three quarters of the heat supplied is lost in friction; heating up the engine cylinder walls, exhaust valves etc., and in the exhaust gases. The heat lost to the cylinder walls is not only useless, it is a direct nuisance. Unless it is adequately dissipated, the cylinder will over-heat. Taking the Silver Ghost as a typical example of a petrol engine. With a 3.9 compression ratio at 500 revs. the heat contained in the petrol supplied is used up as follows:- [Diagram] 18.3% ACTUALLY EMPLOYED USEFULLY PRODUCING B.H.P. 3.7% LOST IN FRICTION. 31.3% LOST TO CYLINDER HEAD & WALLS. 46.7% LOST VIA EXHAUST & A SMALL AMOUNT BY RADIATION. | ||