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 graph showing Mean Effective Pressure and Ignition Advance against RPM for a modified cylinder head.
| Identifier | ExFiles\Box 134\2\ scan0190 | |
| Date | 1st February 1939 | |
| -3- ⑤ CYLINDER HEAD WITH INCREASED THROAT FD{Frank Dodd - Bodies} 292 BUT .070 MACHINED OFF HEAD FACE (COMP RATIO 6.8:1) STD PISTONS SODIUM FILLED EX.VALVES MAX. POWER x---x NON DETONATING. MEP lbs/□" IGN. ADV °BTDC RPM Curve (5) with the cylinder head machined on face by .070 and opened out transfer throat FD.{Frank Dodd - Bodies}292 - 1.64 sq.in, - 6.8 : 1 Compression ratio gives a maximum MEP of 122 lbs. sq.in. at 1500 r.p.m. and detonates on full throttle up to 2500 r.p.m. In retarding the ignition to be clear of detonation 2 - 3 lbs./sq.in. MEP is lost. Continued. | ||