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 plotting ignition advance and B.M.E.P. against R.P.M. for a 4¼ Litre Bentley engine with different configurations.
| Identifier | ExFiles\Box 82\4\ scan0390 | |
| Date | 1st October 1936 guessed | |
| 4¼ LITRE BENTLEY POWER DEVELOPMENT S3 B3. UNIT IGNITION-ADVANCE WITH TURBULENCE ① COMP RATIO 9:1 Ex 22594 A 2-1" 7/8 SU CARBS ON 1" 7/8 PIPE F.B. ORS CAMSHAFT STD ESSO ETHYL PETROL MIN. ADV. FOR MAX. POWER IN PORTS 1.625 IN VALVE 1.700 / 1.800 Ex " 1.350 / 1.400 ② POWER LOSS AND IGN. ADV. TO REDUCE DETONATION TO REASONABLE DEGREE OTHERWISE AS ① ③ COMP RATIO 8.5:1 Ex 20943. PURE BENZOL MIN. ADV. FOR MAX. POWER OTHERWISE AS ① IN PORTS 1.625 IN VALVE 1.600 / 1.700 Ex " 1.400 / 1.350 Left Y-Axis: CRANKSHAFT DEGREES B.T.D.C. Right Y-Axis: B.M.E.P. LBS/SQ IN X-Axis: R.P.M. Graph values: 4775 | ||