Mercury 175hp diesel outboard

The Mercury Racing blog has revealed information about its second “stealth” outboard that will be rarely seen: the OptiMax Diesel Outboard.

The latest military engine was released in conjunction with the start of the 2015 SOFIC (Special Operation Forces Industry Conference), May 19-21, in Tampa.

The engine, displayed in a booth shared with our OEM boat builder partner MAPC (Maritime Applied Physics Corporation), was apparently the talk of the show.

The OptiMax Diesel was designed and developed by Mercury Racing for the U.S. Department of Defense (DoD).

The exclusive spark ignited, direct fuel injected 2-stroke runs on ultra-low sulfur diesel fuel, which is readily available around the globe.

DIESEL OUTBOARD BACKGROUND
Mercury Government Accounts Manager Tony Nahitchevansky explains the history behind the development of our latest military engine.

"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," says Nahitchevansky.

The mandate called for engines to be developed to operate on fuels that meet the following criteria:
1) Improve ship safety by minimizing fire hazards,
2) More economical and more efficient, and
3) Readily available as a single battle space fuel.

HOW IT WORKS
The 3.0 Litre 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 said to be minimal additional training requirements necessary for maintenance.

A two-stage, direct-injection system uses a small charge of compressed air to finely atomise the diesel fuel as it injects into the combustion chamber. Atomising 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 optimises 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.

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

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.

Words by Rick Mackie from the Mercury Racing blog.