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 development experiments, focusing on carburettor performance and power output improvements.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 82 | |
| Date | 11th November 1927 guessed | |
| contd :- -3- The std. Phantom carbs. gives only 80 H.P. at this speed. These experiments indicate that although low depression carbs. are a considerable advantage, they alone will not give us the desired 90 lbs/sq.in. B.M.E.P. at 3000 r.p.m. With the non-detonating alum. head we shall be able to work with higher compression ratios and experiments are in progress with long duration cams, and it is hoped that by this means the high speed power may be improved in a similar way to the 20 HP. It will be remembered that when the power development experiments were carried out on the 20 HP. no great increase was obtained from any one of the experimental modifications when employed singly but considerable improvement was effected when these modifications were combined on the engine. With regard to the difference in distribution between a carb. with a central diffuser nozzle 9 such as Claudel, Stromberg and Zenith - and the type having the discharge holes in the venturi we have at present no very definite information. We have tried only one example of the latter type - a new type Claudel - and the results were not good but we should not like to condemn this type from the results of this one carburetter. We will carry out some comparative tests of the two types. A diffuser type jet appears to be essential for good distribution as we have never had good results with a cold engine using the S.U. carburetter. We should imagine very good results could be obtained on the chassis engine with a constant depression carb. employing a diffuser type jet with varying metering jets. contd :- | ||