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 of BHP vs RPM for a 4 1/4 Litre Bentley engine with different piston compression ratios.
| Identifier | ExFiles\Box 148\1\ scan0035 | |
| Date | 16th December 1938 guessed | |
| 4 1/4 LITRE BENTLEY B.V. S.62. PISTONS (COMP. RATIO) OPEN EXHAUST 1) COMP RATIO 6.6 : 1 (.170 CROWN) (.030 GASKET) 2) COMP RATIO 7.0 : 1 (.330 CROWN) (.060 GASKET) 3) COMP RATIO 7.25 : 1 (.400 CROWN) (.030 GASKET) WRAITH CYL. HEAD (F50213) IN. VALVE F50133 EX. VALVE F50134 BIG BORE EXH. SYSTEM BEST BENT. EXH. SYSTEM CAMSHAFT EX F46550 B.H.P R.P.M. | ||