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).
Report discussing engine power, carburettor performance, and compression ratios for the SS and F.2.B. series engines.
| Identifier | WestWitteringFiles\S\September1928-October1928\ Scan188 | |
| Date | 26th October 1928 guessed | |
| contd :- -2- carburetters, coupled with the refined low speed and metering attributes of our present chassis carburetter. Previous attempts to increase the power have been somewhat masked by the high depression at which the present carb. works. We have run the SS.{S. Smith} engine on an aero RR. Claudel carb. with the choke reduced to result in a reasonably low induction pipe depression. It will be remembered this choke size was determined on the Phantom to give the highest choke depression at the diffuser without materially raising the induction pipe depression. See appended print V.468. We anticipate that the new RR. expanding carb. will give approx. the same power performance, as with the Claudel carburetter. As with the Claudel carb. We may therefore take the curve on V.468 as representative of the power performance expected from the SS.{S. Smith} engine in its present form with 4.5 to 1 compression ratio and the new carburetter. The F.2.B. series engine is given for comparison and it must be remembered that these powers are both with the test bed exhaust system. The test bed exhaust system reduces the max. open exhaust power by 3%. We agree with the suggestion that the comp: ratio can still be further increased from the engine point of view - i.e. not considering the torque reaction side of the question. The Test Dept. say that the F.2.B. series engine is very free from detonations, much more so than the old non-turbulent type head which had a slightly lower comp: ratio and there is the possibility that we can increase the SS.{S. Smith} ratio above 4.5 to 1 without contd:- | ||