RESULTS of three sets of investigations looking to the improvement of internal-combustion-engine performance are set forth herein. The first set was with multiple ignition, the second with high compression, and the third with the comparative behavior of a variable-compression engine when operating as a constant-clearance engine and when operating with constant compression.
The tests with multiple ignition indicate that it increases the power about 9 to 10 per cent at full throttle and generally gives smoother operation than ignition with a single spark-plug, especially on the leaner air-fuel mixtures.
Increasing the compression ratio from 5.3 to 1 to 10 to 1 resulted in a 13-per cent increase in the power developed by the engine.
Operating the engine on the constant-compression principle resulted in a fuel saving of as much as 34 per cent. The thermal efficiency was increased in the same amount, and the exhaust temperatures dropped more rapidly at reduced loads under constant compression than in the conventional constant-clearance operation.
Fixed spark is entirely feasible under constant-compression operation. Combustion is much better than it is with constant-clearance operation and this should result in less carbon deposition and less crankcase-oil dilution.