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).
Engine induction systems, fuel mixture economy, and carburettor settings for power and acceleration.
| Identifier | ExFiles\Box 36\2\ scan 186 | |
| Date | 10th October 1928 guessed | |
| contd :- -2- part in determining the most economical mixture, because further weakening of the mixture past a certain point results in a decrease of the power output at a greater rate than the decrease in consumption. Therefore an engine with poor distribution will have some cylinders working richer and some weaker than that required for for maximum ax economy. Further the weaker cyls. set the limit to which the mixture can be weakened and remain within the range of stable running. We consider our induction system very good, as proved by these tests, but with four carbs. it is very necessary to ensure that each is giving a similar performance and that the mixture control governs each carb. similarly. This condition we ensured for this test by using only one altitude suction valve and joining the top of the float chambers by a balance pipe to give the same float chamber depression in each case. Under throttled conditions, where it is not a question of max. power output, it would seem that the majority of engines are unnecessarily extravagant in fuel when working with the usual weakest maintained mixtures. Of course, usually the mixture ratio is determined by the ability or otherwise of the carb. to accelerate on lean mixtures and it is chiefly to obtain this latter condition of reliable and vigorous acceleration that carbs. have to be set on the rich side. Therefore, means of obtaining good acceleration without the use of over-rich mixtures - such as the high petrol level which is a feature of our carbs. - permits of a more economical setting and gives much better results in the hands of the ordinary Pilots who seldom contd :- | ||