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 Brake Horse Power against RPM to show the effect of valve timing overlap on a standard Bentley cylinder head.
| Identifier | ExFiles\Box 133\2\ scan0101 | |
| Date | 19th November 1934 guessed | |
| BENTLEY SINGLE CYLINDER TESTS. SHEET 1 EFFECT ON POWER OF VALVE TIMING OVERLAP (STD. BENTLEY HEAD) STANDARD BENTLEY CYLINDER HEAD (EB 1517) COMPRESSION RATIO = 6.4 INLET VALVE = 1.400 DIA., EXHAUST VALVE = 1.300 DIA. AEROLITE PISTON ZENITH TRIPLE DIFFUSER CARBURETTOR (32 m/m CHOKE) OPEN EXHAUST NATURALLY ASPIRATED FUEL = DTD 224 AXES LABELS: Left Y-Axis: BRAKE HORSE POWER Right Y-Axis: B.M.E.P. (LBS/SQ.IN.) X-Axis: R.P.M. TIMING TABLE: CURVE | TIMING. | I.O. | I.C. | E.O. | E.C. | OVERLAP 1. | NORMAL BENTLEY | 4°E | 51°L | 51°E | 7°L | 11° 2. | | 2°E | 51°L | 51°E | 4°L | 6° 3. | | 1°L | 51°L | 51°E | 1°L | 0° 4. | BEST AT 3000. | 10°E | 37°L | 53°E | 2°L | 12° 5. | | 7°E | 37°L | 53°E | 1°E | 6° 6. | | 4°E | 37°L | 53°E | 4°E | 0° NOTE: TO PREVENT CRAMPING, THE B.H.P. CURVES NOS. 2 & 5 ARE NOT CONTINUED DOWN TO THE LOWER ENGINE SPEEDS. | ||