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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.

To quantify the fuel consumption and emissions improvements of Direct fuel Injection (DI), measurements were taken from a two-stroke motorcycle engine while operating in premixed, and direct injection mode burning propane. The part-load lean combustion limit was investigated for the DI technique in both premixed and DI modes. Results were compared to a one-dimensional Computational Fluid Dynamics (CFD) model of the engine. Results indicate that a highly stratified mixture can not be achieved due to poor mixing. The DI technique yields significant reductions in HC emissions, and significantly improved fuel economy, though not as good at Gasoline Direct Injection (GDI). Finally an economic analysis indicates that a gaseous fuel DI retrofit system represents a significant cost savings over a gasoline DI retrofit system.

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.