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SUZUKI DF300B

I had a chance to put about 20 hours of hard and fast (40 to 50 mph) ocean running time on Suzuki’s DF350s down in Key West running 150 to 175 miles a day on a 36 Yellowfin CC and a 35 Contender CC with Capt. RT Trosset (239 IGFA world records) and his son Capt. Chris. The speed, fuel efficiency, traction and smooth, reliable performance of these contra-rotating, twin-prop powerplants literally blew me away.
By Capt. John N. Raguso
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SUZUKI DF300B

Suzuki’s new DF300B is built on the identical 4.4L V-6 powerhead, albeit slightly detuned to achieve its 300HP status. With the minimal horsepower difference between the DF350A and the latest DF300B, you might ask, “Why is this engine even necessary?” The easy answer is that a significant number of boat transoms are limited to either 300HP in a single configuration or 600HP for twins. The introduction of the new DF300B solves both problems very nicely and Suzuki did not have to “reinvent the wheel” in the process. The real sleeper is using the DF300B on a single engine transom configuration; it runs perfectly straight with no steering torque!

The DF300B provides superior “grip” on the water when boaters hit the electronic throttle control. This translates to superior performance from start to finish, with improved hole shots, stronger mid-range acceleration, improved top-end speed and enhanced low-speed maneuvering. With the engine’s power distributed over six blades, rather than three, Suzuki is able to reduce the size of the gears and create a sleek, hydrodynamic lower unit that slices through the water with minimum drag. This increased propeller blade surface area and contra-rotating action also delivers exceptional acceleration while eliminating steering torque and providing incredible reverse thrust, an especially important feature for docking and other close-quarter maneuvers. The performance advantages of Suzuki’s contra-rotating propulsion are particularly evident when pushing large, heavy hulls loaded with crew, fuel, bait and gear, just like we did down in Key West on those two long range trips. And when you hit the throttle, it’s like energizing a built in passing gear, the push at the prop is really there and you will notice the difference.

The DF300B’s robust 4.4-liter displacement features a 10.5:1 compression ratio and dual fuel injectors per cylinder for optimum performance and efficiency while using 87-octane gasoline, which is a real game-changer when it comes time to fuel up. By using two smaller fuel injectors, Suzuki delivers a precise amount of fuel to the center of the combustion chamber, improving atomization and avoiding off-center combustion, a common cause of engine knock. Injecting 100 percent of the fuel
into the cylinder at once also keeps the fuel cool, providing up to 3 percent additional power. A dual-louver, direct air intake system on the DF300B helps the engine breath freely for optimum performance while separating out water, spray and moisture for improved reliability. This unique intake system also provides the engine with cooler, denser air for a more powerful combustion cycle. Suzuki’s proven Lean Burn Control Technology helps ensure optimum fuel efficiency at cruising speed and across the entire rpm range. In addition, updates to the DF300B engine cover and improvements in sound management reduce decibel levels evident in the cockpit, even at high engine speeds.

The DF300B features the offset driveshaft engine layout found on other Suzuki outboards, allowing for an overall compact design, along with two-stage gear reduction (2.29:1) for plenty of low-end torque without sacrificing top-end performance. This compact size, light weight (727 pounds for 25-inch shaft model) and easy integration with Suzuki Precision Control drive-by-wire throttle and shift controls make the DF300B a clear choice for rigging on a wide variety of boats in single or twin installations. Other advanced features like Suzuki’s Easy Start, Troll Mode and compatible Multi-Function Display Screens enhance the overall boating experience. The Suzuki DF300B is available in either black or white, to better match the look on your transom.