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).
Table detailing specifications for car engines, including bore, stroke, displacement, clearance volume, and compression ratio.
| Identifier | ExFiles\Box 19\7\ Scan076 | |
| Date | 17th October 1923 | |
| CAR ENGINES. X790 17/10/23 Engine. | Bore. | Stroke. | Displacement. | Clearance volume. | Compression ratio. 20 HP. | 3 | 4 1/2 | 31.809 cu.ins. | 8.787 cu.ins. | 4.618 40/50 HP. High comp: | 4 1/2 | 4 3/4 | 75.6 cu.ins. | 23.42 cu.ins. | 4.25 Med. comp: | " | " | " | 26 cu.ins. | 3.91 Low comp: | " | " | " | 28 cu.ins. | 3.7 E.A.C. High comp: | 4 1/2 | 5 1/2 | 78 cu.ins. | 21.5 cu.ins. | 4.625 Rm{William Robotham - Chief Engineer} | ||