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).
Induction systems, petrol vaporization, and crankcase dilution.
| Identifier | ExFiles\Box 50\3\ Scan131 | |
| Date | 9th July 1921 | |
| CC Mr.F.H.Royce Mr. Belnap Mr. Nadin Mr. Caswell Oy2 - G 9721 July 9, 1921 Mr. Claude Johnson, Managing Director, Rolls-Royce Ltd., London, England. Attention: Mr. Hives. Dear Sir:- Re: Induction Systems In reply to various letters on this subject, it appears that Mr. Hives considers it would be possible to run without a hot spot if only it were possible to distribute an equal quantity of liquid petrol to each cylinder under all conditions of running. We would add to this, that for American fuel it would also be necessary to introduce the petrol in a finely divided condition at all speeds, as otherwise it will not burn completely. Mr. Hives suggests that the cylinder is the most effective hot spot, but we cannot agree that this is so under all conditions of running. In wintertime for ten or fifteen minutes after starting the cylinders are too cool to vaporize American gasoline. Recent experiments on aluminum pistons (reported in the S.A.E. Journal for May) show that even on a Liberty engine with rather light 5" dia. piston and working at 800 revs. full throttle, the temperature of the head ranges from 600° F.{Mr Friese} to 700° F.{Mr Friese} It is reasonable to assume that on a Rolls-Royce car, very seldom working full power, with smaller pistons of fairly heavy section, the head temperature is generally too low to completely vaporize American fuels, which have an "end point" of vaporization of 500°F.{Mr Friese} or more. Hence we can explain, what all our experiments prove, that there is considerable crankcase dilution on the R-R car with American gasoline and the standard pipe, even in warm weather and under fairly hot running conditions, and very much dilution as soon as the weather turns cold. The following particulars relate to samples of oil taken from two cars, 78-NE a high compression English chassis, and | ||