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 plotting the performance increase on a 20 HP engine due to fitting larger valves.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 10 | |
| Date | 31th March 1927 | |
| 20 H.P. POWER INCREASE DUE TO LARGER VALVES. ENGINE N⁰ 11-GII. COMPRESSION RATIO = 5.45 TO 1 OPEN EXHAUST TWO ZENITH TRIPLE VENTURI HORIZONTAL CARBURETTORS. CORRECTED TO N.T.P. 31-3-27. BRAKE HORSE POWER. R.P.M. OF ENGINE. B.H.P. LARGE VALVES. (1.400 DIA). STANDARD VALVES. (1.200 DIA). B.M.E.P. LARGE VALVES (1.400 DIA) STANDARD VALVES (1.200 DIA) BRAKE MEAN EFFECTIVE PRESSURE (LBS/SQ"). 2 | ||