ARB Research Seminar

This page updated June 19, 2013

Low Emission Four-Stroke Outboard Marine Engine Utilizing Catalyst

Jeff Broman, Product Development and Engineering Group, Mercury Marine, Fond du Lac, Wisconsin

March 17, 2010
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


A conceptual project aimed at understanding the fundamental design considerations concerning the implementation of catalyst systems on outboard marine engines was carried out by Mercury Marine, with the support of the California Air Resources Board's Innovative Clean Air Technologies (ICAT) program. In order to keep a reasonable project scope, only electronic fuel injected four-stroke outboards were considered. While they represent a significant portion of the total number of outboard engines sold in the United States, carbureted four-strokes and direct injected two-strokes pose their own sets of design constraints and were considered to be outside the scope of this study.

The integration of catalyst systems on outboards is much more challenging than on other marine propulsion alternatives. Sterndrive and inboard engines are horizontal crankshaft engine derivatives of an automotive counterpart. Outboards on the other hand utilize a vertical crankshaft, open loop cooling, and consist almost entirely of components that were specifically designed for a marine outboard engine application.

This presentation will show how Mercury Marine designed a catalyst system for two families of outboard engines utilizing state of the art processes and design analysis tools. Prototypes of one of the designs were constructed and tested. Results of that testing will be shown that highlight the potential to meet four-star emissions levels and the challenges that will face commercializing this technology.

Speaker Biography

Jeff Broman is a development engineer in the Product Development and Engineering Group at Mercury Marine. Mr. Broman's work at Mercury Marine has focused on engine thermodynamics development, including combustion, gas exchange, emissions, and engine calibration on conventional two-stroke, direct injected 2-stroke, and naturally-aspirated and pressure-charged 4-stroke outboard engines. Mr. Broman has a B.S. in Mechanical Engineering from the University of Wisconsin.

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