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).
Various methods for fuel vaporization and manifold design.
| Identifier | ExFiles\Box 75\2\ scan0245 | |
| Date | 8th August 1921 guessed | |
| Oy2 - G 8821 Sheet #3. (c) The more advanced folk who try to heat the liquid fuel in the pipe without heating the air or vaporized gas. (d) The people like Dorrie who try to collect the liquid fuel and do something with it later to bring it back into circulation. (a) The first class bury the manifold in the water jacket practically without exception, try to break the liquid fuel into as small drops as possible, and swallow the drop in power from the heated air as inevitable. They say, however, that if the liquid is broken up fine enough and the air heated the right amount, the drop in temperature of the air caused by the work of evaporating the fuel, will result in the charge being at a reasonable temperature, not above 150°F.{Mr Friese}, when it enters the cylinder, and all the liquid will be evaporated, if the conditions can be held right, as stated above. Some of them control either the temperature of the air or the opening of the jet by means of a thermostat worked off the exhaust system. The 5th Avenue Bus Co. do the first, while Prof. Anderson recommends the second and lowers a taper needle into the jet as the temperature of the air increases so as to keep the mixture strength constant. Their trouble is that at low speeds full throttle the air speed over the jet is not high enough to break up the fuel, and so it enters the cylinders in the usual sloppy way. And since any induction pipe will behave decently at high speeds, they do not seem to have got anywhere after all. Prof. Anderson (very much set against heating of the manifold) seriously proposes to use experimentally a jet of 50 lbs. or 100 lbs. air blowing across the fuel jet (in a horizontal carburetter) and states that he has proved that he can run an ordinary automobile engine efficiently on kerosene without knocking and without the use of heat, simply by blowing the fuel to pieces with a high pressure jet in this way. (b) Jacketting the manifold at the Tee above a vertical carburetter in the conventional type of T or Y shaped manifold used on 90% of cars, is so common as to be almost a standard. Makers confess to a 5% drop in power from this method, and, if the Liberty is any criterion, they get a lot more after running hard for a short time in the summertime. They do not get plug pre-ignition as a general rule because the plugs are so well water-cooled. Also, as E.P. noted, they detonate quite a lot in hot weather, and get rough on hills from overheating of the mixture, even when they do not actually detonate. But they achieve a real decrease in crankcase dilution and loading up and a fairly quick "get-away" from cold in the winter; also good acceleration. | ||