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).
Technical report discussing issues with fuel collectors, vaporizers, and induction pipes to improve engine performance and reduce smoking.
| Identifier | ExFiles\Box 74\2\ scan0051 | |
| Date | 15th November 1921 | |
| CyS - G 151121 Sheet #2. 1. Either he must have a short period of intense smoking, or 2. He must have liquid kerosene in his engine with all its attendant troubles. Every owner and chauffeur knows the difficulties of using present day gasoline, and we think every one of them will see the force of adopting the less obnoxious course at the cost of a certain period of smoking after a cold start. The pipe with collectors and vaporizers shows improved fuel consumption and improved low speed power, as compared with the average plain pipe or heated manifold. The power at high speeds is not appreciably reduced by the trumpet shaped collectors. We have tried collectors of smaller capacity but they appear to overflow under certain conditions of running, and are not equally effective in preserving the cylinder from wet fuel. We find the collectors and vaporizers have "loading-up" to a great extent. In about 50% of the cases it is practically impossible to get loading up under any conditions except an excessively rich mixture and a long slow pull. In the other 50% it is possible to get loading on a normal mixture with a cold engine and a pull of 15 m.p.h. for an eighth of a mile, but the subsequent missing on acceleration is not more than one or two "beats" and this is not objectionable. These variations in pipes we attribute to the unexplained differences in Induction pipes and throttles which are found at Derby and Springfield. We have isolated one source of variation in the throttle irrespective of the bars in the throttle and are correcting it in future machining of these parts. The boilers collect gas all the time and at all speeds, when using full throttle, and continually boil it off again. The collection is most at low speeds and above 1000 r.p.m. only amounts to a few drops a minute. Loading with any type of pipe has been proved by several tests (not quite numerous enough yet to be absolutely conclusive) to occur in Nos. 2 or 5. This was tested by running on the road without exhaust boxes. One of these cylinders would always miss and throw out black smoke on acceleration after the slow pull. During the pull, the rear three cylinders appear to be richer than the front three, judging by their smoky exhausts. We have experimentally connected the 1/2" drain pipe to the bottom of the boilers and taken a 3/16 pipe from the top of each boiler to the corresponding end of the induction pipe. This provides a circulation for the drained fuel, the liquid flowing into the boilers and the gas passing back into the ends of the manifold. | ||