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 comparison graph for a 2-litre, 6-cylinder Sunbeam G.P. racer engine, showing B.M.E.P. and Horse-Power curves with and without supercharging.
| Identifier | WestWitteringFiles\O\2January1926-March1926\ Scan41 | |
| Date | 27th January 1926 | |
| TWO - LITRE SUNBEAM RACER. 6 CYL. G.P. COMPARATIVE B.M.E.P. AND HORSE - POWER CURVES (1) WITH SUPERCHARGING (6.15 COMP. RATIO) (2) WITH NORMAL INDUCTION (7.2 COMP. RATIO.) AXIS LABELS: Top X-Axis: BRAKE MEAN EFFECTIVE PRESSURE, lbs/sq.in., values 80 to 200. Top X-Axis (secondary): BLOWER PIPE PRESSURE, lbs/sq.in, values 2 to 10. Bottom X-Axis: ENGINE SPEED R.P.M., values 1500 to 5000. Left Y-Axis: B.H.P., values 40, 60. Right Y-Axis (primary): B.H.P., values 20 to 140. Right Y-Axis (secondary): BLOWER PIPE TEMP °C, values 20, 40. CURVE LABELS: B.M.E.P. (SUPERCHARGED) COMP. RATIO=6.15/1. B.M.E.R. (UNSUPERCHARGED) R = 7.2/1. B.H.P. CURVE (SUPERCHARGED) B.H.P. (UNSUPERCHARGED) BLOWER PIPE TEMPERATURES °C. (Dashed Line) BLOWER PIPE PRESSURES (GAUGE) (Dashed Line) TEXT BLOCK: SUPERCHARGER:- DIRECT DRIVEN - ROOTS GIVING 8lbs/sq. in. (gauge) press. at 4500 r.p.m. VANE LENGTH 10 5/8" FUEL:- STD. SHELL + 2.5% WAKEFIELD 'A' FOR LUBRICATING THE VANES. CARB:- SOLEX (48 m/m CHOKE) FITTED TO INTAKE OF SUPERCHARGER, THE DELIVERY PIPE BEING COUPLED TO THE NORMAL INDUCTION PIPE, AS USED WITHOUT SUPERCHARGING. SIGNATURE: V HALLIWELL | ||