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).
Technical letter discussing various fuel mixtures, their compositions, and performance characteristics.
| Identifier | ExFiles\Box 27a\4\ Scan344 | |
| Date | 21th November 1934 guessed | |
| TO DATE -2- 1) 10% "680" spirit 90% Aviation petrol to D.T.D. 224 specification 100 + 4 c.c.'s of tetraethyl lead (not Fluid) per gallon 2nd 2) 20% "680" spirit 50% Benzol 30% Methanol 100 + 2 c.c.'s of lead (not Fluid) per gallon. 1st 3) 20% "680" spirit 60% Benzol 20% Methanol 100 + 2 c.c.'s of lead (not Fluid) per gallon. 3RD From the tests which we have done in this country and in America, we find that one can get good all round results both as regards acceleration, power and reasonable fuel consumption by the use of straight spirits, such as those mentioned in specification No.1, which have been loaded up with lead. It will be easy for you to obtain D.T.D. 224 which, as you know, is an unleaded fuel, in order to make the No.1 mixture. If you find that 4 c.c.'s of lead per gallon is not enough, put in 7 c.c.'s. Should you be apprehensive of your valve condition with so much lead, perhaps Coverley could Stellite some exhaust valves for you. But for competitions, where the running time is not extensive, I should not think you would suffer from valve burning troubles, even with large amounts of lead. You will note that the other two mixtures are very similar and we would suggest that you try these out against the No.1 fuel to see whether you get superior results. I would try the fuel containing 30% methanol first and if you get trouble with this, perhaps the one containing 20% of methanol would give you better distribution. There is rather a lot of light "680" spirit in these mixtures and if you find that you get any freezing trouble, I would reduce this to 10% and put the balance to the benzol. I think the foregoing fuels will be more suitable than the high Methanol sprint mixture, because I am sure that the latter would give you distribution troubles and it would certainly be very expensive on consumption. The Americans have been playing about with commercial Butane which contains about 20% propane, but this is, at the moment, rather difficult to get in this country and without some reasonably extensive tests I would hesitate to use it, because I do not think that it would give a vast improvement in performance, if any, above special fuels made up with the constituents which are easily obtainable in this country. Our experience is that a plain mixture of benzol and petrol breaks down very badly at high compression ratios and unless one employs alcohol with benzol I would not recommend using benzol alone, or with plain petrol. I think that one of the three fuels mentioned will give you the results you require and if you think I can be of any help, I will be pleased to come up at the time you are running the tests so that we can give you the best fuel possible in the time available. Kindest regards, Yours sincerely, H.W. Sand | ||