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).
Power loss in the exhaust silencer, comparing Vauxhall and Rolls-Royce 25/30 engines.
| Identifier | ExFiles\Box 147\5\ scan0133 | |
| Date | 8th July 1937 | |
| -4- Power Lost to the Exhaust Silencer. The Vauxhall '25' develops a maximum of 80 B.H.P. power lost to the exhaust silencer is 6 B.H.P. The 25/30 (R.R.) develops a maximum of 105 B.H.P. and 15 - 20 B.H.P. is lost to the exhaust system. A suggested comparative test would be tofit the Vauxhall silencers to our 25/30 engine, set the engine to develop 80 B.H.P., and see how much power is lost compared with our own silencer. The answer should give an indication of whether it is the stuffing up of the silencer, or the camshaft overlap which is the cause of such loss. In the same way, the two silencers fitted to the engine developing 105 B.H.P. will show the proportionate increase in back pressure against increased power output. On our own engine the R.R. silencer causes twice the back pressure as does the Vauxhall on its own engine. CONCLUSION. In the past, our efforts to improve the petrol consumption of our cars has been confined to individual experiments on no more than one of the factors at a time of those mentioned in this report. Any small gain which has been forthcoming has, therefore, been very difficult to measure. Further, because other factors have in many cases defeated the object of that particular test, as in the case of an ignition system being unable to supply high voltages for leaner mixture strengths. Based on what we have said in this report it is proposed to carry out a first test as follows, correcting as many of the variables at one go as best as we at present know how. 25/30 H.P. Car. Petrol supply line from the rear tank to be brought along the frame on the outside to a point near the front of the engine, where it goes through the frame. Connect by flexible pipe to a pipe carried round the front of the engine, supported by clips to hold it away from the metal structure to a filter which is part of the connection to the float chamber. | ||