Search Results

To quantify the friction and wear characteristics of TiC coatings, a small two-stroke engine is operated with both coated, and un-coated piston and rings on a fan-type dynamometer for a given length of time. Fuel consumption and power were monitored during the runs and motored friction was measured both pre- and post-run. Surface analysis consisting of photography, Scanning Electron Microscopy (SEM) imagery, and x-ray diffraction of the piston and rings were compared before and after the runs to quantify coating durability. Frictional load results and fuel consumption data were analyzed indicating the approximate efficiency gains for the coatings compared with the stock engine parts.

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.