The study on the effects of different opening ranges of waste-gate on improving the work parameters of spark ignition engine

The experimental study was conducted to investigate the effects of different opening ranges of waste gate of a turbocharged medium displacement spark ignition engine on improving work parameters such as exhaust emission, torque characteristics and fuel consumption. The object of the experimental tests was an engine with modified intake and exhaust manifolds. The intake and exhaust manifold modification included only implementation of turbocharger with the variable geometry turbine. The values of boost pressure were controlled by the system with waste gate valves with a changeable characteristic and a control valve. Work parameters of waste-gate valves have been selected experimentally. Boost pressure had to be reduced to 1.3 and to 1.5 bar in the range of medium values of throttle opening. The system with waste-gate allowed to increase significantly the torque value at low engine speed range as well as to reduce the boost pressure at high engine speed range for throttle opening values above 50%. In total range engine work, emission of particular exhaust gas components did not exceed the values of the emission suitable for normally aspirated engine. It provided the stable engine’s running in all conditions including variable engine speed and in the whole range of throttle opening angle with restricted fuel consumption. The application of changeable characteristics in the waste gate valve which reduces the charging pressure by controlling characteristics variable of the valve depending on the engine work parameters was controlled by electronic system. The controlled system allows improving parameters of engine performance in wide range of engine’s rotation speed.