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).
Test bed runs comparing the performance of Solex carburetors against the standard Phantom carburetor, focusing on B.M.E.P. gains.
| Identifier | WestWitteringFiles\T\2January1929-June1929\ Scan114 | |
| Date | 7th February 1939 guessed | |
| contd :- -2- horizontal distributing pipe (see appended print). Runs were made on the test bed with various chokes and diffusers and the power and B.M.E.P. obtained are shewn on appended prints together with corresponding figures taken with the standard Phantom carb. for comparison. The very appreciable gain in BMEP. obtained with the Solex, particularly at the lower speed range, will be observed from the curves. At 1000 r.p.m. the 34 mm. chokes increase the BMEP. from 100 lbs/sq.in. (given by the standard Phantom carb.) to 112 lbs/sq.in. which is a much appreciated gain at this speed and becomes manifest on the road by improved acceleration. With the 32 mm. chokes the maximum power - occurring at 2500 r.p.m. - is approx. the same as given by the standard Phantom carb. but the Solex gives an appreciable gain in BMEP. at lower speeds. High BMEP. at the lower speed range is a characteristic of induction systems which supply three cyls. from one choke and we have many times observed the same result, both on car and aero engines. The reason appears to be the elimination of overlapping of suction strokes which occurs when one carb. supplies six cylinders so that each cyl. can take full advantage of the kinetic energy of the charge after the piston has reached bottom centre. The total gain observed in this case cannot all be credited to the three port induction system because the low depression resulting with static carburetters is an important factor. The direct result of using two carbs. is to lower the induction depression. contd :- | ||