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).
Carburetter performance tests, comparing speed, petrol consumption, and other improvements between different systems and needle types.
| Identifier | ExFiles\Box 122\4\ scan0204 | |
| Date | 31th October 1938 | |
| -3- MAXIMUM SPEED. Maximum speed remained the same with both systems at 79 - 80 M.P.H. PETROL CONSUMPTION. Constant speed consumption curves for both systems are attached. Choice of needles for the S.U. carburetters lay between 'Z' needles, which have been used on test beds, B.J.A., B.J.B, and B.J.C. needles. The latter two types were found to be too weak below 30 M.P.H, hence consumption tests were only carried out on needles labelled 'Z' and B.J.A. It will be seen from the curves that the former are badly down for consumption, hence all the foregoing tests were carried out with B.J.A. needles. CONCLUSIONS. Substantial improvements were recorded using the S.U. carburetters and Bentley Ill system. These amounted to - (1) A saving in fuel of between 5 and 10% between the speeds 30 and 60 M.P.H. (2) Approximately 10% improvement in performance due to improved acceleration. (3) No loading up when the engine is pulled down on the brake at full throttle. ......... Offsetting these advantages over the Stromberg carburetter and induction system were the following items - (1) Objectionable air intake noise. The tests were carried out with the small double ended air silencer. This trouble would in all probability be ended by using the larger silencer now used on S.B.V, but which would not fit on 28.G.VI in its present form. CONT'D | ||