Mercury Racing® is well known for its line of high performance consumer and race outboards. For the United States government, the Fond du Lac, Wisconsin-based company released a second “stealth” outboard today that will be rarely seen: the OptiMax Diesel. Developed for the U.S. Department of Defense, this exclusive spark ignited, direct fuel injected two-stroke runs on ultra-low-sulfur diesel fuel, which is readily available around the globe.  

“A Navy ship crash in 1995, which resulted in an explosive gasoline fire, spawned a DoD directive for all gasoline-powered engines and gasoline fuel tanks be removed from Naval ships by 2010,” said Tony Nahitchevansky, Mercury Marine government accounts manager. 

The mandate called for engines to be developed to operate on fuels that are:

1) Able to improve ship safety by minimizing fire hazards,

2) More economical and more efficient, and

3) Readily available as single battle space fuel.

The 3.0 Liter V-6 Diesel, which produces 175 propshaft horsepower, shares 95 percent of its components with the gasoline engine from which it derives. And, with only a handful of unique parts, there are minimal additional training requirements necessary for maintenance.

Industry Exclusive Direct Fuel Injected – Spark Ignited Diesel 

A two-stage, direct-injection system uses a small charge of compressed air to finely atomize the diesel fuel as it injects into the combustion chamber. Atomizing the fuel into a fine mist allows for ignition via spark to occur, while delivering enhanced high rpm running quality. A glow plug works in concert with the spark plug for improved cold weather starting and idle quality. An on-board Propulsion Control Module (PCM) microprocessor optimizes fuel and spark timing for improved running quality and performance throughout the engine’s operating range. SmartCraft® Engine Guardian provides real-time, self-protection engine fault diagnostics and messaging.

Race Derived Powerhead 

The advanced 3.0-liter powerhead, customized with a unique cylinder head designed specifically for combustion of diesel fuel, is matched with high-performance cylinder liners for maximum horsepower and optimal engine running quality.

Race Inspired Graphics

The OptiMax Diesel features stealthy, tone-on-tone graphics that feature the new Mercury Racing word mark – similar to those featured on the new Racing Verado 400R consumer performance outboard models. Mercury Racing OptiMax Diesel outboards are available with a 25-inch (635 mm) center section and the 2:1 Fleet Master gearcase in both right-hand and left-hand rotation.