Performance Controlling of Spark Ignition Engine by the Variations of the Intake Valve Opening Angle

The performance controlling developed by a spark ignition engine, with indirect fuel injection, is made through the throttle valve, which regulates the air flow used by the electronic injection system to dose the fuel amount to be delivered, maintaining the suitable air/fuel rate. The FIAT 1580 cc 16V engine was modified to function with only one cylinder. The tests for performance evaluation were conduced in engine tests cell at diverse loads configuration. Seeking the fuel consumption reduction, it was designed a mechanical device that allows, with a working engine, the angular position variation of one of the intake camshaft cam, maintaining the cam of the other valve in its normal synchronism. This process is characterized by the late intake valve closing. It is presented the results of the engine performance trials, operating with and without the throttle valve control system, for many engine load configuration. The results achieved in the break tests shows a considerable reduction in the fuel consumption in partial loads of 75, 50 and 25%.