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).
Analysis of liquid petrol accumulation in induction pipes leading to cylinder misfiring and results from various tests.
| Identifier | ExFiles\Box 75\2\ scan0224 | |
| Date | 25th May 1921 | |
| contd:- -2- Hsl/LG25.5.21. we could obtain the same effect on any make of car with This is a fault I experienced a good deal with 4.EX Car in U.S.A. At first we assumed that this trouble was caused by petrol collecting either in the throttle or in some part of the induction system. We proved, however, that all types of carburetter or induction pipes if we made the conditions bad enough (poor petrol and cold engine). This loading up effect appears to be due to the fact that when there is a quantity of liquid petrol in the induction pipe it clings to the pipe by surface tension this is maintained until a certain velocity is reached in the induction pipes, then a quantity of it leaves the pipe with a rush, and being badly distributed into the cylinders, causes one or more cylinders to misfire owing to richness. We have observed that when we get the best carburation, this same loading up effect takes place, but owing to the fact that there is much less quantity of petr in the pipe or, owing to the fact that the excess petrol is evenly distributed to each cylinder, it is not noticed because of the cylinders firing evenly. The induction pipe with the glass windows showed that at the speed at which we get excess petrol, there is a disturbance in the pipe as though the petrol is suddenly picked up and carried through to the engine. 5. We could observe in the pipe with the glass windows the effect of altering the throttle by putting in the additional stud to counteract the effect of the boss. We could plainly see a bias on the petrol which was corrected by adding the stud. 6. The windows in the glass pipe showed us that the petrol did not impinge on to the branch pipe from the pipe crossing over the engine. At low speeds, what happens, is, that the petrol clings to the surface of the pipe and as soon as it reaches the "T" joint it is wisked off in either direction. We have carried out a number of tests on standard induction pipes to see what variation we obtained in results. We find that with good petrol we get comparatively little variation in the induction pipes but as soon as we start using inferior petrol which means that as soon as we start getting more liquid petrol in the induction pipe, we can notice a very big variation in standard pipes chosen at random. Hot Spot Tests. In connection with the tests with a hot spot we have used | ||