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June 27, 2006

Suzuki 150- and 175-hp Four-Strokes

A well-known outboard-industry executive recently said, Building a two-stroke is relatively easy...

A well-known outboard-industry executive recently said, "Building a two-stroke is relatively easy. It's just a block with some holes drilled in it and a metal plate covering the holes. I could build a two-stroke engine in my garage. A four-stroke is much more advanced and complex." It's safe to say that Suzuki has mastered that complexity.


 Type: 4-IL DOHC 16-valve.
Displ 175 cid
 Bore X stroke 3.81 X 3.81 in.
 Max rpm


 HP/LB ratio 0.32/0.36
Fuel system Multipoint
  Digital EFI
Gear Ratio 2.5:1
Weight 465/474 lb.
Alt. output 44 amps
MSRP $13,687(150-hp)
$14,375 (175-hp)

Larry Vandiver, marketing director for Suzuki Marine, says, "These big-block outboard motors build on the advances we have made in four-stroke engine performance. Our philosophy is very simple... there's no replacement for displacement."

Thanks to a new lower unit and gear case with a final drive ratio of 2.50:1, the lowest gear ratio in the class, Suzuki's DF150 and DF175 can handle larger-diameter, higher-pitch propellers for better low and midrange torque. In addition, both engines have the largest displacement of any four-strokes in this horsepower range, yet they are the lightest. In fact, at 465 pounds, these engines almost match the weights of Suzuki's previous two-stroke 150-hp outboards. That's a distinct power-to-weight ratio advantage.

The distinctive shape of Suzuki's spherical-bore throttle body produces smoother airflow when the throttle begins to open, resulting in improved throttle control and stable engine operation at low rpm. Suzuki adds a water-cooled
heat exchanger to lower the temperature of the fuel before it reaches the engine, increasing the fuel's density for increased power output.

Power is critical for the proper functioning of the outboards' electronic-control module (computer) as well as nav instruments. The heat generated by the hefty 44-amp alternator and voltage regulators inspired Suzuki to augment the system with water cooling for improved reliability and longevity. Both motors also come with a standard battery-isolator system. You can drain down your boat's house battery by powering trolling motors, electronics or livewell pumps while still maintaining a fully charged cranking battery. When you start the motor, the system senses the low charge in the house battery and quickly brings it up to full charge.

Other unique features of Suzuki's engines include a chain-driven counterbalancing system mounted to the front of the block to cancel out horizontal vibrations, along with a thrust mounting system that absorbs engine vibrations at speeds under 2,000 rpm. Suzuki also offsets its driveshaft, providing a lower engine profile while shifting the outboard's center of gravity forward on the transom for better balance and smoother operation. And finally, two freshwater flush ports make flushing the cooling system easy, even with the boat in the water.

Suzuki no longer manufactures two-stroke outboards, and all the company's current products enjoy three-star ratings from the California Air Resources Board.

For more information, contact American Suzuki Motor Corporation at 714-996-7040 or visit