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 results of power tests on a PII unit, comparing performance with an open exhaust versus a standard silencer.
| Identifier | ExFiles\Box 14\6\ Scan214 | |
| Date | 9th October 1931 guessed | |
| POWER TESTS ON PII UNIT. TWIN CARBS RR 1.400 DIA: CHOKES R TYPE PHANTOM SHAFT 110° TIMING AS ON 4 G.31 4.9 COMP: RATIO HEAD WITH DOUBLE VALVE SPRINGS TAPPETS SET { EXHAUST .008, INLET .006 BAR. 758 M/M.{Mr Moon / Mr Moore} B.H.P R.P.M. OPEN EXHAUST WITH STANDARD SILENCER SYSTEM FITTED | ||