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Introducing direct injection technology into two stroke engines can greatly improve the exhaust emission and fuel efficiency. In this paper, we investigate LPG direct injection from the transfer port of a loop-scavenged two stroke engine. The injector nozzle is placed in an area where it can inject through the transfer port window directly into combustion chamber with minimal fuel spillage into the port and minimal loss of fuel to the exhaust port. Several portions and orientations are simulated to determine the best injector nozzle location and orientation. The simulation results indicate that high fuel trapping efficiency is possible with the proper location of the injector and injection timing. Experimental results show an 80% reduction in exhaust emissions with the transfer port mounted injector nozzle compared to the baseline carbureted engine.

Two-stroke engines are common for small transportation units in many South Asia countries. Due to high fuel losses during the scavenging process the pollution emitted by these two stroke vehicles is significant. In this paper, we investigate the details of a gaseous fuel direct injection system using liquid petroleum gas (LPG). A series of three-dimensional, computational fluid dynamic (CFD) simulations are run on various injection geometries, evaluating the air/fuel mixing of the resulting in cylinder charge. The results of the simulations indicate the best injector placement based on air fuel mixing and the best location to install the spark plug.