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Mercury's 4-stroke, 150hp outboard motor is one of the most advanced ever designed.
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Just launched at the Ft. Lauderdale Boat Show back in October, Merc’s new 150 Four-Stroke is a revolutionary new engine design that is simplicity itself. It’s bound to make a lot of new fans in the coming months as boat owners upgrade either their power plant or their ride during the winter boat show season.

The goal of the Merc engineers for their new 150 Four-Stroke was to create a next-gen outboard that was the lightest in its class with the smallest transom profile while offering the largest displacement of any 150 on the market, use fewer parts for maximum reliability and durability and to do it at a price point that was $2,500 less than the most popular competitive 150s. They have succeeded in this task with the new 150 Four-Stroke, which has met all of its design parameters and more.

Despite this naturally aspirated engine’s smaller size and lower weight (only 455 pounds), the new Mercury 150-Horsepower Four-Stroke boasts a 3.0-liter, four-cylinder in-line configuration that easily creates superior power for single or twin applications. Its massive 183-cubic-inch block offers more displacement than any other 150-Horsepower four-stroke engine, yet it delivers fuel efficiency at cruising speed that few can beat.

The powerful torque curve of the new 150 Four-Stroke ensures that even the heaviest boats will plane quickly. If you’re looking for room to fish, this engine fits nicely under poling platforms on flats boats and is easier to fish over and around than all competitive engines of equal horsepower. It’s also the perfect option for boaters choosing to repower their boats, especially older models with transoms not designed to accommodate the added weight of conventional four-strokes. Mercury’s new outboard weighs just 24 pounds more than their popular OptiMax 150 direct-injected two-stroke.

Despite the expansive list of desirable features and benefits, Mercury’s new 150 Four-Stroke is also affordable, priced about $2,500 less than most competitive four-stroke 150-Horsepower outboards. The new 150 Four-Stroke is designed, built, and tested to be the most reliable and durable 150 on the planet. The new 150 Four-Stroke has been subjected to thousands of hours of hardcore, severe duty testing in some of the most remote corners of the world, experiencing abuse that the average boater would never endure in a lifetime of operation.

The new Merc 150 Four-Stroke is one of the world’s easiest 150-Horsepower outboards to rig, with standard mechanical cables, dual cable or hydraulic steering compatibility, optional power steering on dual-engine set-ups and the ability to run on either standard analog or full SmartCraft instrumentation straight from the factory. All connections under the cowl for throttle and shift cables, data harnesses, etc. are easily located and accessed for quick, intuitive, hassle-free rigging. It’s also compatible with Mercury’s innovative Big Tiller system.

Repowering is also quick and easy. The new 150 will connect to any steering, Mercury rigging or instrumentation currently in the boat, or whatever the consumer wants to upgrade in the dash or console. The new Mercury 150 contains almost 20 percent fewer parts than competitors’ 150-Horsepower engines, further enhancing durability with less parts to have to either maintain, repair or replace. The Mercury 150 Four-Stroke proves that technology can be used equally well to deliver durability and performance while simultaneously reducing package size and weight.

One of my favorite features on the Merc 150 Four-Stroke is the low-friction SOHC (single overhead cam) valve train, which uses race-proven roller finger followers and oversized valves that are a less complex design. This new-wave valve train has no shims to adjust and is totally maintenance free! Now that’s a major revelation that will save you a costly $700-$750 valve adjustment every 300 hours of use, as required by most competitive four-stroke outboards. Other user-friendly features found on the Merc 150 Four-Stroke for do-it-yourselfers include an overall engine design and layout that makes it easy to perform routine maintenance; a no-mess oil change system; no tools needed to change the onboard fuel filter; color-coded maintenance locations; an up-front freshwater flushing system; plus a single latch, lightweight cowl for easy on and easy off operation. If you have an aversion to reading the operations guide and maintenance manual, there’s a handy reference decal located on the inside of the engine with an easy-to-follow maintenance schedule on what to replace and when to do it.

The 150-Horsepower EFI Four-Stroke features Mercury’s standard three-year limited, non-declining warranty and will be eligible for promotional warranties. If I follow through with my plans and pick up a used 20-footer to prowl the bay, inlet and beach areas, this new Merc 150 Four-Stroke is on my radar screen as the preferred repower of choice.

Propshaft Horsepower- 150
Max RPM- 5000-6000 rpm
Cylinders- 4-in-line, 8 valve SOHC
Displacement- 183 cubic inches (3.0 liters)
Bore & Stroke- 4.0-in x 3.6-in (102mm x 92mm)
Induction System- Multi-port EFI
Alternator- 60-amp, belt driven
Gear Ratio- 1.92:1
Emissions Rating- 3-Star CARB (ultra-low)
Steering system- mechanical (standard); hydraulic, power steering and tiller optional
Recommended Fuel- 87 octane gasoline, max 10% ethanol
Shaft Lengths- 20-inch and 25-inch
Weight- 455-lbs (20-inch shaft)