A six cylinder, four stroke petrol engine with a bore of 120 mm and stroke of 180 mm under test, is supplied petrol of composition : C = 82% and H2 = 18% by mass. The Orsat gas analysis indicated that CO2 = 12%, O2 = 4% and N2 = 84% by volume. Determine (i) that air-fuel ratio and (ii)the percentage of excess air.
Also calculate the volumetric efficiency of engine based on intake conditions when the mass flow rate of petrol 32 kg/min at 1600 RPM. Intake conditions are 1 bar and 170C. Consider the density of petrol vapour to be 3.5 times that of air at same temperature and pressure. Air contains 23% oxygen by mass.