Studies on an Air Assisted Gasoline Direct Injection System for a Two-Stroke Engine

In this work a two-wheeler two-stroke spark ignition engine was modified to work in the air assisted direct injection (AADI) mode with gasoline as the fuel. Standard mechanical hardware was used. The controller for this system was developed in-house using a FPGA based system-using Labview software. The system controlled the fuel injection, mixture injection, lubricant pump frequency and the spark timing. Preliminary experiments were conducted at 3000 rpm to determine the influencing variables and potential of this system. Mixture injection timing was an important variable. The AADI system reduced short-circuiting of the fuel and the maximum brake thermal efficiency went up from about 21% with the carbureted version to 26%. There was a significant drop in HC levels from about 1500 ppm to 400 ppm with the AADI mode. NO levels went up slightly due to improved combustion. The overall equivalence ratios were considerably lower than the carbureted version as the short-circuited portion mainly contained air. The present results indicate the potential benefits of this system, which can be easily implemented on a two-stroke engine.