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 20 HP power increase due to larger valves and lower induction pipe depression.
| Identifier | ExFiles\Box 5a\5\ 05-page042 | |
| Date | 31th March 1927 | |
| 20 H.P. POWER INCREASE DUE TO LARGER VALVES AND LOWER DEPRESSION IN THE INDUCTION PIPE. ENGINE No. 11-GXI COMPRESSION RATIO - 5.45 to 1. OPEN EXHAUST Corrected to N.T.P. 31-3-27 B.H.P. B.M.E.P. LARGE VALVES (1.400 DIA) AND TWO ZENITH TRIPLE VENTURI HORIZONTAL CARBURETTERS. B.H.P. B.M.E.P. STANDARD VALVES (1.200 DIA) AND R.R. CARBURETTER. BRAKE HORSE POWER BRAKE MEAN EFFECTIVE PRESSURE (LBS/SQ") R.P.M. of ENGINE. 3 | ||