Mercury Is Building a 600-Horsepower V-12 Outboard Motor

Last year, Volvo shuttered Seven Marine, which built outrageous outboards based on supercharged GM LS V-8s. What to do, then, if you want a 600-hp outboard (or three or four) to throw on the stern of your modest runabout? Don’t worry, Mercury has you covered. And no, they didn’t crank their supercharged 4.6-liter V-8 up to 600 horsepower. They went naturally aspirated, with a 7.6-liter V-12.

That’s right: a V-12 outboard. You may have questions, such as “Huh?” And, “Wha?” Perhaps you’re wondering how they fit all those cylinders and pistons into a package that would bolt right onto a transom and then be able to, you know, steer and stuff. Well, you could say they had to do things a little differently with this one.

The original 100-hp Mercury outboard was called the Tower of Power because it was so tall. They ought to revive that nickname for this one, since since that V-12 block is mounted straight up and down, with the open side of the V pointed rearward. Normally, outboard-powered boats steer by pivoting the whole engine and drive as single unit. But with 12 cylinders filling up the cowl, Mercury had to figure out a different approach—every inch counts when you’re trying to cram as many outboards as humanly possible on the back of your center console. So instead of pivoting the powerhead and lower unit, the V-12 Verado simply swivels the lower part of its outdrive. It’s going to be disconcerting to see one of these leave the dock, the boat swinging around while the engines point straight ahead.

If you’re thinking maintenance will be a nightmare with 12 cylinders to fetter, Mercury anticipated that pain point and tried to make the V-12 easy to deal with. There’s a hood on the top of the cowling that allows owners (or their minions) to handle the 200-hour oil change without removing the cowling or taking the boat out of the water. The cowling does come off for the major service, but that one’s only every five years or 1000 hours. Mercury is also offering a commercial version called the SeaPro that’s designed to rack up huge hours and take plenty of abuse. That one is detuned to 500 horsepower, but a couple of those would get your trawler moving pretty good.

While a 600-horse V-12 sounds like the epitome of hey-look-at-me outrageousness and ostentation, Mercury makes the case that these beasts actually represent pragmatic boating. One benefit: fuel economy. How is a 7.6-liter V-12 good for fuel economy? Because to get 1200 horsepower, you’d use either two of these or, say, three 425-hp V-8s. In which case, you still have 24 cylinders, but the added drag of another drive in the water. Mercury says dual V-12s deliver 20 percent better fuel economy than triple (Yamaha) V-8s.

Less drag is good for speed, too. Mercury bolted three of the V-12s to a 31,500-pound Boston Whaler 420 Outrage and saw it hit 63.7 mph. By comparison, a quad-engined 420 Outrage with Verado 400s topped out at 54.1 mph. Yes, the triple V-12s deliver 200 more horsepower than the quad 400s, but that kind of speed difference is a much bigger delta than you’d expect from 200 horsepower—especially considering that the 400-powered boat weighed about 1700 pounds less.

The V-12’s transmission likely helped the cause. Yes: the big Verado compounds its power advantage by incorporating a two-speed automatic transmission in the lower unit. First gear is 20 percent lower than second gear, to help the boat get up on plane. We’d assume that allows Mercury to run props that are pitched for high speed, since the launch gear can compensate in low-speed situations that call for lots of torque.

The really intriguing part of this, for aquatic speed freaks, is that this isn’t a Mercury Racing engine. It’s a standard Verado. The way this normally works is that Mercury introduces a naturally aspirated version of a given outboard, and then a couple years later Mercury Racing reveals a supercharged version. That’s what happened with the V-8s—first came the 300-hp Verado, followed by the supercharged 450-hp Mercury Racing 450R. So if these things are 600 horsepower without a blower, what kind of power might they make with some boost? Somewhere on Lake X, Mercury’s secret test lake in Florida, we’d guess there are some 800Rs running laps. But let’s put the over/under on 750 horsepower.

Used to be, you’d need at least a couple engines to hit that kind of power. Maybe not for much longer.

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