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 Brake Horse Power and Brake Mean Effective Pressure of a standard 20HP engine against a modified version.
| Identifier | ExFiles\Box 19\7\ Scan109 | |
| Date | 1st April 1927 guessed | |
| 20HP POWER INCREASE DUE TO HIGHER COMPRESSION RATIO, LARGER VALVES AND LOWER DEPRESSION IN THE INDUCTION PIPE. ENGINE N° 11-GII. OPEN EXHAUST CORRECTED M.T.P. BRAKE HORSE POWER B.H.P. B.M.E.P. STANDARD 20 H.P. (OPEN EXHT.) B.H.P. B.M.E.P. 20 HP ENGINE WITH LARGE (1.400 DIA) VALVES, 5.45 TO 1 COMP. RATIO & TWO ZENITH TRIPLE VENTURI HORIZONTAL CARBURETTORS. R.P.M. OF ENGINE BRAKE MEAN EFFECTIVE PRESSURE (LBS / SQ") 4 | ||