Heywood J.B [3] in his text clearly indicated that, to ensure complete combustion even with latest technologies the engines must operate in excess air. That is, more air carrying 21% O2 by volume is passed through the intake valve than the chemically required (stoichiometric) and this process ensures that nearly all fuel molecules receive required oxygen for complete combustion. Excess air speeds up the mixing of fuel with air and ensures complete combustion of fuel but at the same time excess air wastes heat energy by carrying it in the exhaust gases. If sufficient oxygen is not provided to the engine during combustion process, complete conversion of carbon and hydrogen is impossible to attain and that leads to particulates and carbon monoxide resulting in increased exhaust emissions.