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 20HP engine power increase due to modifications including higher compression, larger valves, and lower induction pipe depression.
| Identifier | ExFiles\Box 5a\5\ 05-page043 | |
| Date | 31th March 1927 guessed | |
| 20HP POWER INCREASE DUE TO HIGHER COMPRESSION RATIO, LARGER VALVES AND LOWER DEPRESSION IN THE INDUCTION PIPE. ENGINE NO. 11-G-II OPEN EXHAUST CONVERTED F.I.P. B.H.P. B.M.E.P. 20 HP ENGINE WITH LARGE (1.625 DIA) VALVES, 5.45 TO 1 COMP. RATIO & Two ZENITH TYPE VERTICAL-HORIZONTAL CARBURETTORS B.H.P. B.M.E.P. STANDARD 20 HP (OVER PAGE) BRAKE HORSE POWER. R.P.M OF ENGINE BRAKE MEAN EFFECTIVE PRESSURE (LBS/SQ") 4 | ||