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).
Carburettor design, proposing a new system with a diffuser jet to improve performance over existing models.
| Identifier | Morton\M11\ img153 | |
| Date | 11th March 1919 | |
| To EH. from R.{Sir Henry Royce} CARBURETTORS CONTD. (2) R5/G11319. and the varying speed depending upon the road dangers. I have sent Mr. Southern a sketch of a carburettor arrangement which may turn out useful, and which apparently can begin at the smallest dimensions, and yet give ample area, maintaining a constant vacuum. With a constant vacuum carburettor, it is necessary to vary the size of the petrol passage, as well as that of the air passage, and I think we ought to test all of the carburettors that have been made on these lines. For a long time I have thought that the missing feature of this type of carburettor is the diffuser jet, which you will see is applied in the system suggested. Combining the idea of the diffuser jet and sufficient heat in the induction pipes, carburettor throttle, etc., and possibly warm air to the carburettor would, one thinks, enable us to make a carburettor which will beat our existing one. (will be very difficult, when successful heated the engine runs wonderfully well) These carburettors, such as our own present standard, and the Smiths multi-jet, always stand at a disadvantage when an additional jet is cut in. It is for this reason, that the carburettor should be of the expanding type, as originally fitted to our own two-cylinder cars, which has appeared in various patterns, namely, Brotherhood, Bradley, Polyrhoe, S.U., Stewart's Precision etc. Originally, an R.R. carburettor with a moving petrol needle was tested on a two-cylinder engine, and therefore was working at a considerable disadvantage. It was, however, extremely good at slow speeds, but was thought by me not to be as practical as a single jet one with an extra air valve. This carburettor might be used for experimental (Contd.) B'H' S22' (200 L) (R'D' 402' 89-4-71) B'W' S12QU? | ||