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).
Engine detonation, preignition, fuel distribution, and manifold design.
| Identifier | ExFiles\Box 75\2\ scan0240 | |
| Date | 2nd August 1921 guessed | |
| Oy2 - G 2821 Sheet #2. You find that detonation (? "chirping" or "fuel knock") becomes too bad for the car to run, before preignition takes place. Our preignition was intermittent and alarming, occurring as a sudden shock - like a jumping toothache - in an engine which was not chirping. I think that is all I can say on this subject, and I think it explains why we think it necessary to thoroughly try out any hot spot arrangement with American fuel before fitting it to all cars. (3) Distribution: The consensus of opinion in the States just now is that within limits the particular design of the induction pipe does not matter very much if a hot spot device is fitted which is effective in supplying dry gas to the cylinders at all speeds, so long as each cylinder is fed with about equal freedom from "wire drawing". They are as anxious and worried about this subject as we are, and have all spent a lot of time and money in experiments. The above opinion was stated by the Fuel Research Committee of the S.A.E. last winter, after long experiments. They think over here that, with old time gasoline they used to feed it dry into the cylinder. I think your pre-war glass pipe experiments prove that this was never done. But the fact remains that they feed it a lot wetter now and that it is more necessary than ever to feed it dry, because heavy ends slopped into the cylinder will (1) dilute the crankcase oil, (2) cause knocking, (3) cause carbon deposit, (4) waste fuel through coming out of the exhaust unburnt. I would say that an effective hot spot which performs its function of supplying dry gas, makes possible a complete revision of one's ideas on manifold design. For instance, a pipe of this form:- A | ||