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 engine explosions in the exhaust manifold under different throttle and carburettor settings.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan051 | |
| Date | 13th August 1926 guessed | |
| contd :- -4- For the next experiment the engine was motored at 1000 r.p.m. with the carburetter mixture control normal and the throttle adjusted until explosions took place in the exhaust manifold and no firing of the charge occurred in the cylinders with the open exhaust ports. Petrol vapour was then sprayed in front of the exhaust ports by means of a syringe when it was found that under these conditions the cylinders would start to fire again in exactly the same way as if richened up from the carburetter. This shews that there is a to and fro flow between the exhaust manifold and the cylinder and supports the statement that when the manifold becomes charged by small additions of charge from the carburetter, it will tend to enrichen the contents of the cylinder sufficiently to ignite. Considering now case (2) in which explosions are obtained when the throttle is opened after being shut for coasting, the reason does not seem far removed from case (1). We know that a certain throttle opening will have to be given corresponding to the motoring speed before the charge will fire regularly. Therefore a certain amount of live charge will be passed through into the manifold, before the first fire occurs in the cylinder and ignites it. Case (3) - where explosions occur sometimes after the throttle has been closed is a little different and we think the cause is due to the following :- As the throttle is shut after normal running one or two charges will pass through unfired owing to the exhaust contd.. | ||