Life Assessment of PM, Gaseous Emissions, and Oil Usage in Modern Marine Outboard Engines

Recently, outboard engine technology has advanced significantly. With these new technologies comes a substantial improvement in emissions compared to traditional carbureted two-stroke engines. Some two-stroke gasoline direct injection (GDI) marine outboard engines are now capable of meeting California Air Resources Board 2008 Ultra-Low emissions standards. With improvement of gaseous emissions, studies are now being conducted to assess particulate matter (PM) emissions from all new technology marine outboard engines which include both four-stroke and two-stroke designs. Methods are currently being developed to determine the best way to measure PM from outboard engines.

This study assesses gaseous and PM emissions, mutagenic activity of PM and oil consumption of two different technologies over the useful life of the engines. Water testing was performed on both engines to identify percentage of oil and grease present in a tank after running the engine according to the International Council of Marine Industry Associations (ICOMIA) cycle. One of the most significant differences between lubricating oil usage from two-stroke and four-stroke engines is accountability of oil in terms of where it goes and who is responsible for it. Results are presented and a better understanding of effects of engine lubricating oil usage from both an environmental and legal standpoint is discussed. Final PM and gaseous emissions results averaged over the useful life of both engine technologies are very similar. The two-stroke GDI engine used 25% less oil over the 300 hour test program.