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).
Performance graph of B.HP and B.M.E.P. vs R.P.M. for a 20-25 HP China Unit engine with various valve timings.
| Identifier | ExFiles\Box 102\5\ scan0121 | |
| Date | 29th August 1932 | |
| V1320, 29-8-32, 20-25 H.P. CHINA UNIT, 5.75:1 COMP. RATIO, CAMSHAFT. E57177. (108°), STANDARD CARB., B.H.P., B.M.E.P., R.P.M., EARLY TIMING, LATE TIMING, C.I.S., TDC, BDC, EX., IN., 1°, 6.1°, 34.1°, 46.5°, 7.8°, 28.5°, 49°, 7°, 14°, 43°, 35° | ||