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).
Comparison of carburettor performance, focusing on choke sizes, manifold depression and power output.
| Identifier | ExFiles\Box 13\3\ 03-page113 | |
| Date | 21th October 1929 guessed | |
| -2- This we considered, was evidence that the larger restrictor employed with the larger choke was restricting the air flow to the choke. We then removed the two inner walls of the float chamber so as to provide an unrestricted entry to the mouth of the choke. Fuel was fed to the carburetter from an independent float chamber. The immediate result was an increase in power as shewn on appended curves. The power now approaches that given by the R.R. C.H. carburetter. Upon further examination of the results and comparison with the R.R. C.H. carburetter, we find several interesting differences. The R.R. C.H. carburetter - which gave very good power - was fitted with a choke which gave a free area of 1.53 sq. in.. This gave a manifold depression of 1.9" Hg. and a choke depression of 3" at 2500 R.P.M. The R.R. expanding carburetter had a free choke area of 1.95 sq. in. (27% larger) but gave a manifold depression of 2.45" Hg. and a choke area of 2.9" Hg. with a corresponding reduction in power. This shews that the pressure restoration between the choke and induction manifold, is not as good as with the R.R. C.H. carburetter. The disadvantage being that it is necessary to employ large chokes with corresponding low suction in order to get a low manifold depression. An experiment was now tried in which the restrictor was removed and in its place was substituted the | ||