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).
Comparison of the performance characteristics of Discol and Esso-Ethyl petrols.
| Identifier | ExFiles\Box 150\1\ scan0315 | |
| Date | 31th January 1938 | |
| COMPARISON OF FUELS. Tests have been carried out on Discol and Esso-Ethyl petrols in order to compare the following qualities - (a) Power. (b) Consumption at weakest Maintained. (c) Detonation and spark advance characteristics. (d) Pre-ignition and valve temperatures. (e) Petrol level and needle modifications. (a) Power. The difference in power output for the two fuels is negligable when running with weakest Maintained mixture strength and spark advanced for maximum power. The greatest difference being 2 lbs. B.M.P. at 3000 r.p.m. (See attached curve B.V.132.A.) The curves are corrected for barometric pressure and temperature. (b) Consumption at weakest Maintained. Discol fuel has to be run up to 10% richer than Ethyl in order to get maximum power. This applies mostly between 2000 and 4000 r.p.m. (See B.V.132.A.) (c) Detonation and Spark advance characteristics. Power loss due to retarding the ignition to avoid detonation is less with Discol than with Ethyl. With the minimum spark advance for maximum power detonation using Discol is slight and is only apparent up to 1000 r.p.m. Detonation is heard up to 2000 r.p.m. with Ethyl and is worse than Discol. Discol does not need as much spark advance as Ethyl for maximum power ( See B.V.132.D. (d) Pre-ignition and Detonation. There is no difference between the two fuels for pre-ignition and valve temperatures. The valve temperature figures are given below:- Discol. Ethyl. 4000 R.P.M. 805°C. 807°C. 3500 r.p.m. 778°C. 777°C. continued. | ||