Mercury Racing has built a new diesel outboard for the United States government. The OptiMax Diesel is a spark-ignited, direct fuel-injected two-stroke outboard that runs on ultra-low-sulfur diesel fuel. The government asked for a diesel outboard after the Department of Defense asked that all gasoline-powered engines and tanks be removed from Naval ships by 2010.
The 3.0-liter V-6 diesel produces 175 propshaft horsepower and shares 95% of its components with the gasoline version of the outboard. The 3.0-liter powerhead is customized with a cylinder head designed for combustion of diesel fuel and it’s matched with high-performance cylinder liners for maximum horsepower. The two-stage, direct-injection system uses compressed air to atomize the diesel fuel as it injects into the combustion chamber. Atomizing the fuel lets ignition occur while delivering high rpm running quality. A glow plug works with the spark plug for improved cold-weather starting and idle quality. An onboard Propulsion Control Module (PCM) microprocessor optimizes fuel and spark timing. SmartCraft Engine Guardian provides real-time self-protection, diagnostics and messaging. Finally, the OptiMax Diesel features stealthy two-tone graphics. The diesel outboard is available with a 25” center section and 2:1 Fleet Master gearcase in right- and left-hand rotation.