Experimental research on operational process of petrol engine on lean air-and-fuel mixtures on the edge of combustion knock

The results of experimental research are provided regarding the operational process of VAZ-21124 petrol engine with the compression ratio of 12.0 on lean air-and-fuel mixtures with various values of heating the air charge at intake, and of the ignition advance angle. In the course of performing the experimental research, the pressure of gases in the engine cylinder was registered, as well as the temperature of the air charge in the intake manifold, the ignition advance angle, and the concentration of toxic components in the exhaust gases. The obtained pressure indicator diagrams were processed using a special program for determining indices of the operating cycle, cycle consumption of fuel and air, air excess factor, and heat release rate. The obtained cycle consumption of fuel and air, as well as the air excess factor were compared to the ones measured experimentally. As a result, possible boundaries of leaning of air-and-fuel mixture were revealed, as well as the values of heating the air charge, and of the ignition advance angle, for intensification of the process of combustion till the knock moment. When the air charge temperature at the intake was raised from 29°C to 112°C;, the ignition advance angle retarded from 35.5 to 15 degrees, and the air excess factor decreased from 1.55 to 1.41 respectively. (paper)