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 report comparing the efficiency, power loss, and weight of various intake silencer designs.
| Identifier | ExFiles\Box 179b\2\ img175 | |
| Date | 28th November 1932 | |
| -4- Scheme 2. fig 4. Hs{Lord Ernest Hives - Chair}780. Tests shewed that to get the best results it was necessary to have a certain length of intake. Also that the efficiency depended not only on the capacity of the chambers and the point of their connection to the intake, but on the disposition of the capacity. That is, the large chamber surrounding the small one was not quite as efficient. (diag.4). In any case the optimum length of intake required detracts from any particular merit on grouping these chambers together. Generally speaking with this type situated close to the carburetter, it is not quite so easy to get 100% results as with the more remote location. We find that the use of a felt lining to the chambers, while having little or no effect on 'roar' is very beneficial in the elimination of 'tinniness' which is apt to be noticeable when thin gauge material is used. TYPE OF SILENCER SILENCING EFFICIENCY LOSS OF POWER ON P.II.150BHP. AT 3500 RPM. WEIGHT WITH COMPLETE INTAKE & ATTACHMENT TO CARB.BODY Standard RR. for Semi-Expanding Carburetters. 25% 2% 3 lbs.2 ozs. Smallest above (Induction Pipe(1). 100% 4% 4 lbs.4 ozs. * Intermediate above Induction Pipe(2). 95% 1% 4 lbs.8 ozs. Largest above Induction Pipe (3) 100% Nil. 5 lbs. * Silencer adjacent to intake. 95% .8% 4 lbs.4 ozs. American Silencer Burgess for Chrysler. 37. BHR 90% over 10% 5 lbs.14 ozs. with no intake. * Sizes recommended for Prod. | ||