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).
Performance graph comparing a high power head against a standard 3 1/2 litre Bentley engine on a water brake dynamometer.
| Identifier | ExFiles\Box 134\2\ scan0108 | |
| Date | 13th February 1937 | |
| BENTLEY S/C UNIT COMPARISON OF HIGH POWER HEAD LEC 4075 AND STD BENTLEY FIG I ON H AND F WATER BRAKE ① HIGH POWER HEAD INLET VALVE 1.750" DIA ② STANDARD 3 1/2 LITRE BENTLEY INLET VALVE 1.700" DIA B.M.E.P. 140 130 120 110 100 90 80 R.P.M. 1000 2000 3000 4000 B.H.P. 22 20 18 16 14 12 10 8 6 J.L.E 13-2-37 | ||