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 curves for three different types of Bentley cylinder heads.
| Identifier | ExFiles\Box 86\1\ scan0039 | |
| Date | 30th November 1933 guessed | |
| BENTLEY SHEET 1 FLOW - CU.FT. / MIN. PRESS: DIFFERENCE ACROSS VALVE - INS. HG. COMPARISON OF AIR FLOW CURVES FOR (1) STD. BENTLEY HEAD - EB 615 (1.4 DIA: VALVES) (2) LARGE VALVE BENTLEY HEAD (1.5 DIA: VALVES) (3) ALUMINIUM HEAD - EB 1337 (1.5 DIA: VALVES) (1) (2) (3) | ||