Beyond 3 Star Emission Capability for Outboard Engines

This paper investigates strategies intended for development towards Super Ultra Low emission levels (4 Star) from the existing 3 Star emission status for 2 stroke Direct Injection and 4 stroke outboard engines. The current 5 Mode ICOMIA outboard emission status is considered for Hydrocarbons, Nitrogen Oxides and Carbon Monoxide. From these a gap analysis is developed and possible strategies to close the gaps are considered. The potential of these strategies for 2 stroke air assisted Direct Injection outboards is reviewed together with supporting data where appropriate. Initial data show high potential for reduction of emission levels beyond the 3 Star standard, whilst further work will confirm the levels that may be feasible in a production outboard engine.