Graph and analysis of Mean Effective Pressure and Ignition Advance against RPM for a cylinder head test.
| Identifier | ExFiles\Box 123\5\ scan0285 | |
| Date | 1st February 1939 | |
| -7- RE/Swd1.2/MR.1.2.39. ① CYLINDER HEAD THROAT OPENED OUT TO PD 292 (SODIUM FILLED EX.VALVES) FLUSH TOP PISTONS 6.4:1 COMP RATIO ------- MAX POWER x-----x NON DETONATING MEP lbs/sq in IGN. ADV. °BTDC RPM IGN MEP Curve (1). Cylinder head as originally designed including opened out throat PD.292 - 1.75 sq.in. in conjunction with normal flat top pistons but flush with the top of the cylinder block and not .030 down as standard. The maximum MEP is 128 lbs/sq.in. at 1500 r.p.m. and there is no detonation at maximum power throughout the speed range. From the ignition advance curve it will be seen that it is necessary to over advance at all speeds before detonations come in. Another test we have not recorded is the modified head PD.334. This extends the effective length of the combustion chamber and reduces the sandwich area between the piston and the head. This condition is by far the worst experienced for detonation etc., such that it was not possible to record any figures. | ||
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).