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).
Engine performance report on plug position, power output, and detonation tests.
| Identifier | ExFiles\Box 134\2\ scan0138 | |
| Date | 23th August 1937 | |
| -3- (4) PLUG POSITION. Two plug positions were tried, one over the throat, and one over the exhaust valve. The throat plug was selected as best, because (i) Detonation was at a minimum and power a maximum. (ii) Ignition advance was practically identical to standard Bentley. The exhaust plug gave far too great an advance - 40° at 1000 R.P.M. (iii) Slow running with weak mixtures was better. All figures quoted in this report, therefore, are for a KLG.850. plug in the throat position. (5) POWER OUTPUT. It was decided that for this engine, the chief requirements were low speed power, absence of detonation, and smoothness of running. (a) Smoothness. This is dealt with above under "Ignition Advance." (b) Low Speed Detonation. Power curves were run at constant detonation intensity of 6", on a paraffin-shell mixture, and results are as shown on Fig. 4. Percentage gains over standard Bentley were calculated to be:- 1000 1500 2000 2500 3000 3500 3750 4000. Max. Power 6.40 9.10 9.30 5.00 5.84 10.70 15.70 21.80 6" Detn. 7.20 11.05 9.56 9.20 10.72 14.00 19.10 20.60. It will be observed that the gain at constant detonation is considerably more than the gain at maximum power, a strong point in favour of the high power head. (c) Valve Timing Lift, etc. A considerable number of valve timing tests were made together with tests on valve size, lift, etc., and as far as possible it has been decided to separate the inlet and exhaust systems. | ||