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).
Graph plotting power loss for a 20/25 HP engine using an open exhaust, resonance silencer, and standard silencer.
| Identifier | ExFiles\Box 104\2\ scan0068 | |
| Date | 9th November 1932 guessed | |
| 20/25 HP RESONANCE SILENCER POWER LOSS I ① OPEN EXHAUST ② RESONANCE SILENCER ③ STANDARD SILENCER EXHAUST BACK PRESSURE INS. HG 10 5 S.H.P 70 60 50 40 30 20 10 B.M.E.P 110 100 90 80 70 60 50 R.P.M 500 1000 1500 2000 2500 3000 3500 4000 | ||