Characteristics of Four Stroke Compression Ignition Spark Ignition Engines Characteristics Compression-Ignition Engine Spark-Ignition Engine Compression Ratio 14-22:1 5-8:1 Ignition Compression Electric Spark Thermal Efficiency 30-60% 25-30% Fuel induction Injector Carburettor (Fuel Injection) Fuel System Fuel Oil /Diesel Gasoline LP gas) Fire Hazard Less Greater Power Variation Increase in Fuel Increase in Air/Fuel Mixture Air Induction Constant Variable(Throttle Airflow) Air-Fuel Ratio 15-100:1 10-20:1 Relative Fuel Consumption Lower Higher Energy per litre of fuel Higher Lower Manifold Throttle Absent Present Exhaust Gas Temperature 482°C/900F 704°C/1300F Starting Harder Easier Lubricants Heavy duty oils Regular and Premium Oils Speed Range Limited(600-3200 rpm) Wide range (400-6000 rpm) Engine Mass per Horsepower 8kg17.51b) Average 4 kg(9 1b) Initial Cost High Much Lower Lugging ability (Torque) Excellent Less 上游充通大学 Monday,May 08,2017 7 SHANGHAI JIAO TONG UNIVERSITYMonday, May 08, 2017 7 Characteristics of Four Stroke Compression Ignition & Spark Ignition Engines