Yanmar BMW Diesel: 6BYZ260

Test driving Yanmar/BMW 260 horsepower marine diesel sterndrive

Yanmar Marine teamed up with BMW automotive to bring high performance, common rail diesel engines to the marine marketplace.

Yanmar BMW turbo diesel>

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Yanmar Marine's line marine motors includes a
pair of marinized, BMW turbo diesels rated 220 and 260 horsepower. Stern
drive and inboard models are available. Both the
6BY220Z and the 6BY260Z are inline six-cylinder motors featuring common
rail, direct injection with vertical injectors. Predictably firmware and
electronics manage to finesse maximum horsepower per cubic inch and still
turn in enviable fuel economy. Did I mention these engines are
uncharacteristically quiet for a diesel? Further blasphemy, they don’t
smoke. Another worthy item is the instrument panel that talks to the engines
via CAN bus, displaying vital numbers on a multi function gauge
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In Miami I tested
the first one to hit the water, a 260 horsepower In-line six bolted up
against to a MerCruiser Bravo Three stern drive. The platform was a Regal
Commodore 2665, a 29 foot cruiser, a model that‘s been around for awhile.
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The Yanmar marinized BMW is intercooled and turbocharged. That means a
huge volume of cold, dense air (full of oxygen) is forced into the
combustion chamber, building more torque than ought to be legal. So
naturally acceleration comes on strong. Because it’s a common rail diesel,
smoky exhaust is virtually eliminated, fuel economy is stellar and most of
the characteristic diesel rattling has been silenced. A MerCruiser stern
drive is an important part of the package. Spinning its twin, counter
-rotating propellers, the Bravo Three drive leg amplifies engine performance
by about 30 percent. That means perkier acceleration and greater mileage,
when compared to a conventional single propeller stern drive. Twin wheels
also grab the water better, improving maneuvering at all speeds and in both
forward and reverse gears. In short, what we have here is a potent performer
with impeccable handling manners. I also like the ample electrical output
that comes standard.
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On this boat, on this bright and shiny day, cruising speed (best mileage)
was bracketed between 32 to 34 mph. We caution readers that this was a
prototypical installation and performance numbers, while certainly
impressive, will undoubtedly improve in production engines as fuel mapping
and propeller sets are dialed in to the nth degree. Also important to note,
in the interests of fair play we did not test sound levels. This for the
simple reason the cockpit sole was not sound insulated. Recall the package
was a prototype. Stay tuned for future tests conducted on production boats.
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Yanmar 6BYZ260
Rated horsepower	198 @ 3600 rpm
Maximum Horsepower	260 @ 4000 rpm
Cylinder configuration	I-6
Displacement	2.9 L - 183 CID
Aspiration	turbocharger with intercooler
Combustion	Direct injection, common rail
Weight	683 pounds
Alternator output	150 amps
Stern drive	MerCruiser Bravo Three

Two thirds fuel load (50 gallons), no freshwater and six men on board. 85 degrees Light chop, light wind. Conducted on the waters of the Intracoastal waterway between Miami and Miami Beach.