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).
The influence of hot spot temperature on engine detonation, including a graph.
| Identifier | ExFiles\Box 66a\1\ scan0100 | |
| Date | 2nd February 1926 guessed | |
| contd :- -15- HEAT ADDED AS %AGE OF HEAT GIVEN TO WATER BY CYLINDERS. %AGE INCREASE R.P.M. INFLUENCE OF HOT SPOT TEMPERATURE ON DETONATION. All the experiments were carried out on a Phantom engine having a compression ratio of 5.2 to 1. With this ratio and ordinary commercial shell Mex petrol - which was also employed throughout the tests - detonation was very severe at low speeds with full throttle. A test was made at 1000 r.p.m. full throttle in which the outlet pipe from the hot spot exhausted in-to the atmosphere to give us the maximum possible temperature, the ignition being then adjusted until there was just no audible detonation. This was repeated with a cold hot spot when it was found that the respective spark positions were 22° B.T.C. with heat, and 25° B.T.C. without heat - a difference of only 3°. When operating with the ignition giving maximum power we could not appreciate any difference in the intensity of detonation between the hot and cold conditions. Accelerating under load from a low speed was accompanied by severe detonations but no difference whatever could be detected in this respect with either hot or cold hot spot. contd:- | ||