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).
Test report page comparing specific fuel consumption and B.M.E.P. for different engine hot spot systems.
| Identifier | ExFiles\Box 66a\1\ scan0095 | |
| Date | 2nd February 1926 guessed | |
| contd :- -10- The method of making the test was varying the mixture strength over approx. its maximum range of steady running and observing the corresponding values of the torque and consumption. The following curves of specific consumption in terms of pts/B.HP/Hr. are plotted against the B.M.E.P. By this means we are able from the one set of curves to observe the variation in the maximum B.M.E.P. and the minimum consumption for the various hot spot temperatures occurring with each system under full load conditions. In order to ensure as accurate a comparison as possible the same hot spot was used for each test and was adapted for each system in turn. We know that the total heat supplied to the charge depends not only upon that supplied by the hot spot but also upon that carried in by the air. Therefore we kept the outside air temperature as near as we could the same for each test (approximately 33 to 40°C). Looking at the curves taken at 750 r.p.m., we noticed that there is practically no difference in the maximum B.M.E.P. with either system but that the specific consumption at the point of maximum B.M.E.P. is considerably less with the standard system than with the water heated system. <strikethrough>About .55 pts/B.HP/Hr. is the corresponding figure with the</strikethrough> About .55 pts/B.HP/Hr. gives maximum torque with the standard hot spot whereas .64 pts/B.HP/Hr. is the corresponding figure with the water hot spot. The superheated system falls between these two with a value of approx. .600. contd :- | ||