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 airflow through different engine cylinder heads against pressure difference across the valve.
| Identifier | ExFiles\Box 31\2\ Scan136 | |
| Date | 26th September 1938 guessed | |
| SHEET 3 FLOW CU.FT./MIN COMPARISON OF HEADS 8 LITRE BENTLEY HEAD ALL TAKEN AT FULL LIFT PHANTOM - .480" BENTLEY - .335" STD E82458 VALVE FITTED TO P.I. REQD. E.83808 (LARGE VALVE HEAD) P.I. STD. HEAD - E.83538 PRESS. DIFF. ACROSS VALVE - INS. Hg. | ||