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 mechanical efficiency versus RPM for a 4¼ Litre Bentley engine.
| Identifier | ExFiles\Box 133\1\ scan0210 | |
| Date | 13th April 1937 | |
| 4¼ LITRE BENTLEY MECHANICAL EFFICIENCY INDUCTION SYSTEM: TWO 1 S.U. CARBS AND STANDARD INDUCTION PIPE. EXHAUST SYSTEM: STANDARD TEST BED SILENCER CYLINDER HEAD: STANDARD 4¼ LITRE BENTLEY HEAD INLET VALVE: 1.600" DIA EXHAUST VALVE: 1.400" DIA COMPRESSION RATIO: 6.8:1 FUEL: D.T.D. 224 VALVE TIMING: STANDARD BENTLEY WATER TEMPS: INLET 78°C; OUTLET 85°C OIL TEMPS: INLET 80°C MECHANICAL EFFICIENCIES 1. STRAIGHT MOTORING (solid line) 2. CUTTING OUT CYLINDERS (dashed line) - RPM - MECHANICAL EFFICIENCY Fig. V E.D. 13.4.37 | ||