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 performance of three different exhaust silencers on a 3.5-litre engine.
| Identifier | ExFiles\Box 138\1\ scan0273 | |
| Date | 23th June 1936 | |
| 23rd June, 1936. EXHAUST SILENCER TESTS. 3 1/2 LITRE ENGINE. | R.P.M. | B.H.P. | | | Back Pressure per sq.in. | | | |---|--- |--- |--- |--- |--- |--- | | | 1. Manifets Standard | 2. American Silencer | 3. Servais | 1. | 2. | 3. | | 3,000 | 76.0 | 84.0 | 88.5 | 3.7 lbs. | 2.5 lbs. | 2.0 lbs. | | 3,500 | 94.0 | 96.0 | 100.0 | 5.4 " | 3.2 " | 2.6 " | | 4,000 | 99.5 | 102.0 | 106.5 | 6.7 " | 4.3 " | 3.4 " | | 4,500 | 101.5 | 107.0 | 112.0 | 8.1 " | 5.3 " | 4.3 " | Baffle Plate Type - 9 lbs per sq.in. at 4,000 R.P.M. Note: The Servais Silencer gives better silencing effect than the other two. --------- | ||