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).
Discussion of various manifold designs intended to improve fuel vaporization to compensate for poor quality gasoline.
| Identifier | ExFiles\Box 75\2\ scan0246 | |
| Date | 8th August 1921 guessed | |
| Oy2 - G 8821 Sheet #4. It is a fairly general impression that they have got a long way to go to even catch up with the growing poorness of the gasoline. (c) The attempt to heat the liquid fuel only is gaining ground. Ever since Chalmers brought out the "hot-spot" "Rams horn" manifold about 1917, the other makers have been trying to improve on it. A lot of them took and used the scheme in the meantime, however; for instance Hup, and most of the separate engine makers. The idea of course was to bounce the liquid fuel across the manifold on to the hot plate by making the manifold thus:- [Diagram showing a cross-section of a manifold with handwritten labels] Exhaust Pipe Supposed course of liquid fuel It was later shown, however, that the liquid actually hugged the lower side of the Tee at most speeds, and this scheme gradually has come to be considered scarcely more effective than just jacketting the manifold. I believe it is agreed, even by Chalmers, that they lose power. They say, however, quite correctly, that the loss of maximum power is of no importance since any automobile is run under 1/4 load or so for 95% of the time. Also, they get a very quick acceleration because it is not necessary to charge up the pipe before they can get mixture to the cylinders, on suddenly opening the throttle. The later designs of engine are beginning to use a "hot stairway", like the Ansted engine in the Lexington, or a "hot concertina" like Nelson on the Premier. (S.A.E. Journal February.). Both of these schemes are intended to expose a big heating surface to the fuel without heating the air much, and also to trap the fuel in the corrugations of the hot wall, so that it cannot get past without being boiled away. The Packard fuelizer claims to be included in this class, though whether it can be I do not know. They reckon to inject a small amount of burnt gas, at high velocity and very high temperature (say 2000°F.{Mr Friese}) across the path of the main gas flow, and so to vaporize | ||