Effect of Compression Ratio, Mixture Strength, Spark Timing, and Coolant Temperature Upon Exhaust Emissions and Power

A single-cylinder engine operating at constant speed using gasoline as fuel was used to study the effects of compression ratio, mixture strength, spark timing, and coolant temperature upon exhaust emissions and power for a part-throttle condition. Of these variables, mixture strength and spark timing had the largest effect upon exhaust emissions, followed by coolant temperature with compression ratio having minor effects. Spark timing followed by compression ratio had the largest effect upon power and fuel consumption.