Mercury’s New V-6 3.4L Outboards

Mercury Marine maps a new trajectory in the race for outboard supremacy.
Mercury's New V-6 3.4L Outboards
Mercury’s New V-6 3.4L Outboards Garrett Cortese

If you were a boater growing up in the ’50s and ’60s, you had your eye on two techno races: the Space Race to the moon between America and Russia, and the outboard horsepower battle between Mercury and Evinrude.

We settled the race to the moon, but the race for outboard horsepower supremacy has simply never stopped to this day, and other brands such as Yamaha, Honda and Suzuki have entered the contest.

It was the latest round of “if you build it, they will come” that recently brought me, along with a select group of America’s boating press, to Mercury’s legendary, top-secret test facility on Lake X in central Florida.


There, we learned Mercury had defied most rumors of pumping out a new 600-horsepower outboard to take a shot at the Seven Marine 627. Instead, it introduced a completely new line of four-stroke V-6 3.4-liter outboards that might redefine boater expectations when it comes to marine power.

But the biggest surprise was just how big a blastoff these new engines would be. Cranking out 175, 200 and 225 horsepower, Merc’s new FourStroke V-6 motors are designed to change the contest from maximizing raw horsepower to creating more elegantly designed, naturally aspirated, superior-handling outboards.

Mercury's New V-6 3.4L Outboards
In speed runs, it exceeded 50 mph and accelerated to 20 in just about 3 seconds. Pretty snappy. And it worked equally well on single applications, like Mako’s 21 LTS and Lowe’s 230 Retreat pontoon. Courtesy Mercury Marine

Now, on the test basin of Lake X, we were looking at more than a dozen boats powered with motors that were designed to eliminate many of the old liabilities four-strokes needed to overcome. These were pontoons, center consoles, bay boats, deck boats and walkarounds. We would soon learn these motors proved ideal for all of them.


Through nearly 20 years of research and development in four-stroke outboard technology, motors that were originally fat and slow have been slimmed down, while boats were redesigned with more beam and freeboard at the transom to support beefier motors and dual, triple and quad installments.

Yet Merc’s new motors are even lighter, weighing in at just 475 pounds, lighter than all competitive four-strokes, and even 21 pounds less than the two-stroke Evinrude E-Tec G2 V-6 and a dozen or so pounds less than Yamaha’s four-cylinder 175.

In addition to dropping weight, this new engine platform disposed of many other maintenance liabilities inherent with four-strokes. In many existing platforms, oil changes are messy, usually drooling oil all over the block. And valve trains needed periodic and expensive adjustments or shimming. Just checking the oil level was an ordeal usually ignored due to the difficulty of removing the cowling before hunting for the dipstick.

Mercury's New V-6 3.4L Outboards
Remove the cowl by lifting the lever and using it as a handle to lift it. Courtesy Mercury Marine
Mercury's New V-6 3.4L Outboards
Check and add oil in the same spot. Courtesy Mercury Marine

With the new FourStroke series, gone are multiple awkward cowl latches. There’s a single latch and handle nested beneath a small cowl-top hatch that functions like the gas tank cover on your vehicle. Push to open it. Push to latch it.

Gone also is the treasure hunt for the dipstick and oil-fill cap buried deep in the motor’s guts beneath a nearly impossible-to-remove cowl. Check your oil under that same hatch in the top. Add oil there too.

Gone are expensive valve-train adjustments. The valves on these new motors self-adjust for the life of the motor; it’s unlikely you’ll ever need to look under the cowl at valves.

Mercury's New V-6 3.4L Outboards
The 24-valve system is ultra-responsive and provides rewarding power and smooth idling. Courtesy Mercury Marine

Gone is the demand for pricier digital throttle and shift controls. Mercury’s new motors, while operating on coveted but expensive digital throttle systems, have cable-capable controls inside, so repowering a boat is possible with a choice of digital throttle and shift or standard cable controls likely already installed on the repowered boat.

Gone is the leaning, lightbulb shape of the Verado motors. These are angular, sharp and poised like a hatchet to attack the competition.

Gone is the monochrome color choice of black or white. Now you have not 50 shades of gray but an unlimited number of color combinations thanks to four factory, optional color panels, plus a primer-coated panel to custom-paint to match your boat. And these panels are applicable to cowls of black or three shades of fusion white.

But we were about to experience what the new motors had gotten as well as what was gone.

Mercury's New V-6 3.4L Outboards
Engine functions can be monitored on digital or analog gauge systems for easy repowering. Courtesy Mercury Marine

We jumped aboard a Scout 275 Dorado with dual 200s and digital throttle and shift. The silky controls enhance the experience because they are so easy to operate and can be adjusted to give just the right amount of friction. Also on board was Mercury’s Active Trim, an automatic system that trims the motors to the ideal position based on an acceleration profile custom-calibrated to any boat. Merc has offered that for a while, but now it can be set and operated through the VesselView gauge. Another new advantage: If you override Active Trim, it re-engages when you stop trimming. There are five trim profiles for the boat, and if you find load or sea conditions require more or less trim, you can select a more- or less-aggressive trim profile from the VesselView gauge. Our engines were linked to the navigation system to display gauge information on the big navigation displays or VesselView screens.

Mercury's New V-6 3.4L Outboards
The 85-amp alternator is nested between cylinder banks for a slim profile. It outputs 20 amps at 650 rpm, but when extra amps are required, the motor automatically boosts idle rpm. Courtesy Mercury Marine

Like past Verados, it’s best to start and stop the motors with the start/stop buttons; leave the key on so the electronics stay active. We idled out of the basin and kicked it up on plane in just a few seconds. Our top speed was just over 50 mph, and the economy gauge read 2.7 mpg when we settled on the most economical cruise speed.

Next, we throttled up to a fast cruising speed of about 4,000 rpm and wound the boat into a sharp turn. One of Merc’s new “haves” is Adaptive Speed Control, and with it the boat held its rpm all the way through the turn as we watched the tachometers hold steadily on 4,000. The most experienced captain couldn’t do this better. In speed runs, it exceeded 50 mph and accelerated to 20 in just about 3 seconds. Pretty snappy. And it worked equally well on single applications, like Mako’s 21 LTS and Lowe’s 230 Retreat pontoon.

Noise management was equally impressive. Special injector covers eliminate the high-pitched noise typically heard from them. Tuned multichambered air intakes further decrease sound (while improving performance), and a new system of seals and vents prevents mechanical noise from escaping and sea spray or water from being ingested when backing down. Further, hefty new vibration-dampening motor mounts isolate more noise. At top speed in the open 21-foot Mako 21 LTS, we were able to converse comfortably.

Mercury's New V-6 3.4L Outboards
Now you have not 50 shades of gray but an unlimited number of color combinations thanks to four factory, optional color panels, plus a primer-coated panel to custom-paint to match your boat. Courtesy Mercury Marine

The Mako sported a mechanical cable throttle system, giving us a feel for that economical setup. The throttle lever controlled the digital actuators under the cowl, and all the digital functions of the engine, including Adaptive Speed Control, operate nearly as smoothly as when controlled with DTS. Further, these new FourStrokes output signals to analog gauges. The ambidextrous ability to use digital or mechanical and analog systems make repowering any boat as easy as unbolting the old one and bolting on this new Mercury plant.

Lake X was the perfect place to reveal Mercury’s newest outboards. The performance of the 175, 200 and 225 hp FourStroke outboards is as important to boating today as that of those developed in the early days of Mercury’s history at this secret facility.

Let the horsepower race begin anew!

Mercury's New V-6 3.4L Outboards
Lake X has played an important part in the history of outboard development. Courtesy Mercury Marine

Lake X

In 1984, Carl Kiekhaefer sold the 1,440-acre Lake X and the more than 10,000 wetland acres surrounding it to the Kirchman Foundation, and Mercury leased the test facility back from it. The preserve is protected by a high fence to this day, and we needed a sheriff escort to gain entrance from the pistol-packing caretaker (cue the snakes, gators and bears).

As motors and boats got bigger through the ’70s and ’80s, the race-course laps got smaller until Mercury let the lease expire to find new testing grounds in southwest Florida, then later in the Florida Panhandle region where high-powered boats couldn’t streak through a test course in 32 seconds.

Lake X’s storied past began in 1957, and everybody who worked for Mercury in those years remembers the secret research facility warmly as the center of outboard history.

The secrecy then was more than just a feint to mystique. Industrial espionage was indeed rampant in the outboard industry. Mercury kept undercover “spies” with big bar tabs at Mathon’s Pub near Evinrude’s engineering facility in Waukegan, Illinois.

Evinrude undoubtedly posted listeners in Fond Du Lac’s favored watering holes for the same reason.

Carl Kiekhaefer was paranoid about spies, and could be seen scouring public test waters with binoculars, looking for binoculars that might be trained in his direction. Lake X was essential to the brand’s uninterrupted work.

Mercury's New V-6 3.4L Outboards
Many new innovations were kept under wraps. Courtesy Mercury Marine

In its day, Lake X had housing for the engineers and a chef, and access was by only one narrow dirt road with the brick remnants of the old Dixie Trail once laid by chain gangs. The road to it today is buttery-smooth, and a handful of rustic but deceptively comfortable cabins dot its shore. The test facility itself is tidy, but clearly seldom used until recently and in need of paint. A rusting three-story observation deck with domed acrylic windows stands sentry at the boat basin’s entrance, an art deco reminder of the days when outboards and spaceships were being designed and built at breakneck speed.

Lake X is open to the public on a limited basis and usually only used for humanitarian missions, like providing outdoor adventure and conservation education for needy and deserving pupils. An equestrian center is also used for special events. For more information about the Kirchman Foundation, visit