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).
Horsepower data for a 20 HP engine with standard and experimental exhaust systems.
| Identifier | ExFiles\Box 113\2\ scan0060 | |
| Date | 20th March 1924 guessed | |
| 20 HP. EXHAUST. HORSE POWER. | R.P.M. | Free exhaust. | Exhaust manifold including hot-spot. | Exhaust pipe from manifold to silencer added. | Silencer added. | Swan neck exhaust pipe added. | |---|---|---|---|---|---| | 1000 | 23.5 | 22.7 | 22.5 | 21.9 | 21.9 | | 2000 | 47.5 | 44.8 | 43.7 | 42.5 | 42.4 | | 3000 | 58.1 | 54.0 | 52.6 | 48.7 | 47.1 | 20 HP. EXHAUST (EXPERIMENTAL). HORSE POWER. | R.P.M. | Free exhaust. | Three exhaust pipes fitted and hot spot. | Front silencer and pipe to silencer. | Silencer added. | Swan neck exhaust added. | |---|---|---|---|---|---| | 1000 | 23.5 | 22.7 | 22.7 | 22.5 | 22.5 | | 2000 | 47.5 | 46.6 | 45.0 | 43.7 | 43.4 | | 3000 | 58.1 | 55.6 | 55.6 | 52.4 | 51.4 | | ||