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 showing the power output of a 20HP engine with specific modifications.
| Identifier | ExFiles\Box 5a\5\ 05-page061 | |
| Date | 7th May 1927 guessed | |
| 20HP POWER OUTPUT WITH THE FOLLOWING MODIFICATION TO STD ENGINE. TWO ZENITH TRIPLE DIFFUSER CARBURETTERS COMPRESSION RATIO 5.45 TO 1 LARGER VALVES 1.400" DIA INLET CAM DURATION INCREASED BY 22° ON C'SHAFT EXH. + 12° EXH CAM LEADS INLET CAM BY 120° CURVES WITH FREE EXHAUST DOTTED CURVES SHOW POWER & MEP BEFORE STRONGER VALVE SPRINGS WERE FITTED B.H.P. - Horse Power ENGINE R.P.M. B.H.P. B.M.E.P. | ||