With the recent introduction of its new top-of-the-line engine, Suzuki Marine offers all the power you want for your outboards. At 350 horsepower, this V6 four-stroke outboard is named DF 350 A and is the most powerful engine never built by the Japanese brand. In development for more than three years, it represents a significant milestone in both engineering and design terms.
“We have put a lot of work into this new outboard and we are looking forward to see how the market responds. We have watched with great interest as boats have gotten bigger, especially the center console market,” said Yasuharu Osawa, Executive General Manager, Global Marine & Power Products Operation, Suzuki Motor Corporation. “Moreover, we’ve seen an increasing preference for outboards on all kinds of boats that used to be exclusively stern drive or inboard. The time is ripe for this new outboard, and we think you’re going to love it” said the manager.
Suzuki engineers hav achieved 350 horsepower without overlooking elements currently considered as essential, such as compact design and light weight. The robust engine displacement of 4.4 liters is matched by a high-performance 12.0:1 compression ratio, the highest ever for a production outboard engine. A unique combination of cool air intake, dual fuel injectors and a strengthening of the pistons has virtually eliminated engine knock, a typical by-product of high compression engines.
Furthermore,Suzuki engineers have designed an air intake system that allows the engine to draw in ample fresh air, while separating it from water, spray and moisture. Dual louvers located under the hood trap larger water droplets and then moisture as it enters the engine cowling, resulting in zero water intake during testing. Moreover, intake air temperatures are, on average, 10º cooler than environment, providing the combustion chamber with cooler, denser air for a more powerful cycle.
The presence of two smaller fuel injectors (instead of a single one) allows for precise injection of fuel to the center of the combustion chamber, which avoids off-center combustion – a major cause of knocking. In addition, because 100% of the fuel is injected into the cylinder at once, a degree of cooling is also obtained, providing up to 3% additional power without causing knocking.
To achieve 350 horsepower, the surface of the piston needs to withstand added forces. In order to assure both performance and long life, Suzuki engineers switched from a standard heat treatment to “shot peening.” Shot peening, a more expensive process, creates fine dimples in the face of the piston that evenly distribute the pressure created during combustion. In addition, the connecting rods and hardware have been strengthened to handle the added loads.
Even though contra-rotating propellers are not somethings new, they have never been successfully used on outboard motors until now. The DF350A’s dual propellers provide three key benefits: compact size, increased stability and greater “traction.”
By distributing the power of the engine over six blades, instead of just three, the size of the gears and gearcase could be kept to a minimum, which in turn allowed for the design of sleeker, more hydrodynamic gearcase. Suzuki engineers spent many hours in computer simulation and on the water, knowing that reducing drag underwater would be essential to improve overall boat speed and performance.
Contra-rotating propellers also provide added surface area, for more stability and increased “traction” or grip underwater. (Think of the wide slicks on a drag racer as compared to typical tires.) This results in exceptional acceleration, or hole-shot, truer directional propulsion (eliminating steering torque), better than expected top speeds and incredible reverse thrust. Importantly, these benefits are apparent even on heavier boats with full loads of fuel, gear and people.
“Even though these new engines benefit from innovative technology, they also take advantage of Suzuki’s proven systems,” added Mr. Osawa. “We wouldn’t call them The Ultimate 4-Stroke Outboards without building in superior reliability and dependability over the long haul.”
The DF350A features Suzuki Precision Control, drive-by-wire throttle and shift controls. Skippers will appreciate smooth shifting, precision control of the throttle, not to mention easier rigging, especially when second stations are involved.
Like Suzuki’s other V6 outboards, the DF350A features Suzuki’s offset driveshaft engine layout, which allows for a more compact outboard and two-stage gear reduction. Two-stage gear reduction provides a larger reduction gear ratio (2.29:1) and more torque for quick acceleration, and improvements in top speed, as well.
Moreover, the DF350A also takes advantage of Suzuki’s Lean Burn Control Technology, for improved fuel economy throughout the entire rpm range, and especially at cruising speed. The DF350A is even extraordinarily quiet at idle.
” We’ve taken all the time we needed to design what we think is the ultimate new outboard motor,” said Mr. Osawa. “The DF350A is ready to take on all the challenges and demands of today’s boats – and deliver a ‘wow’ to skippers who have been looking for new power to handle their bigger boats.”
The DF350A will be manufctuered in Japan, in Suzuki’s Toyokawa-based production sites. After its official debut in the US market next July, it will presented in Italy and all aroud the world from the second half of summer.