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).
List of compression values for various engine types and configurations.
| Identifier | ExFiles\Box 19\7\ Scan022 | |
| Date | 23th July 1920 | |
| R.R. 238a (100 T) S.H. 89. 23-7-20) G 2760 X.790. Compressions of various type engines. 919. Steel pistons, flat-faced valves front 3 cylinders 82, rear three - 86. 945 - Standard engine, long stroke, 8/5 front 85 rear. 786. - Short stroke. 72 front 76 rear. | ||