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 power development for a 4 1/4 litre Bentley engine with various compression ratios and configurations.
| Identifier | ExFiles\Box 82\4\ scan0389 | |
| Date | 1st October 1936 guessed | |
| B.3 UNIT 4 1/4 LITRE BENTLEY POWER DEVELOPMENT S.2 COMPRESSION-RATIO CYL HEAD Ex 22594 (IN PORTS 1.625) CAMSHAFT EB 1085 2 1 7/8 S.U. CARBS ON 1 7/8 PIPE ① COMP RATIO 8.5:1 ② " " 9.0:1 ③ COMP RATIO 6.5:1 (N PORTS 1.350) STD CYL HEAD MOD TO LEC 5002 (DETURBULATED) STD. NON. SYSTEM I.O. 3° BT{Capt. J. S. Burt - Engineer} E.O. 47° BB I.C. 51° AB E.C. 6° AT TAPPETS 0.020 B.H.P I.M.E.P R.P.M CTS{C. Trot Salt - Carburation} | ||