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 comparing horsepower against revolutions per minute for various engine configurations.
| Identifier | Morton\M4.2\ img027 | |
| Date | 1st January 1923 guessed | |
| 4 CYLINDER - 3 1/2 BORE X 5 1/2 STROKE 4 CYLINDER - 3 1/8 BORE X 4 1/2 STROKE 4 CYLINDER - 3 1/4 BORE X 5 1/2 STROKE 6 CYLINDER - 3 1/8 BORE X 4 1/2 STROKE 6 CYLINDER - 3 1/4 BORE X 5 1/8 STROKE 1000 1250 REVS: PER HORSE POWER | ||