Search Results

In pursuit of reducing dependencies on foreign oil coupled with U.S. renewable fuel standards and an overall focus and interest in greenhouse gas emissions, investigations continue on feasibility of replacement biologically derived fuels such as ethanol and butanol. Majority of existing recreational products such as marine outboard engines, boats, personal watercraft, all terrain vehicles and snowmobiles are carbureted or operate open-loop, meaning the engine does not have the capability to sense air-fuel ratio. Ethanol has a specific energy content that is less than gasoline. Without means to compensate for air-fuel ratio requirements of specific fuels, open-loop engines may suffer from a condition known as enleanment, in which catastrophic engine failure may result. On the contrary, butanol has specific energy content closer to that of gasoline, suggesting open-loop engines may be less prone to negative effects of increased biologically derived fuel concentrations in gasoline.

This study investigates the performance of a rope start two-stroke outboard engine, capable of running on multi-fuel, primarily focusing on JP5/8. This engine would be predominantly used worldwide by all departments of the US Military and Special Forces. A two cylinder, direct injected, 30 HP engine was used for research with ongoing development being carried out on larger motors, ranging to 250 HP. The investigation includes the performance characteristics of JP-5/8, gasoline, diesel, kerosene, ethanol and bio-diesel as a fuel, essentially concentrating on power, torque, effects of varying compression pressures on combustion characteristics and soot deposits, detonation characteristics of different fuels, behavior in stratified and/or homogenous combustion and cold start of the engine at temperatures of 0° F.