• The robust engine displacement of 4.4 litres is matched by a high-performance 12.0:1 compression ratio, the highest ever for a production outboard engine.
  • As first impressions go … these Suzuki 350s are superb.

Parting the Waves – Suzuki Style

Digby Fox – freelance journalist, cameraman and producer – takes a first look at Suzuki’s new flagship 350hp V6 4-stroke with revolutionary counterrotating propellers …

As launches go, this one had a wow factor of 10. Smoke, music, big screens, secrecy, a dramatic curtain reveal – all that good stuff. And boom, as you see here, counterrotating props, plus a load of innovation under the hood. Details are in the side panels; here are some first impressions.

Flying in the president of this 26 billion US dollar turnover giant to the launch in Florida was a significant symbol for a culture big on symbolism. Toshihiro Suzuki, the president, took to the stage in front of invited press and boatbuilders from around the world and stated his company’s commitment to building the best marine outboards.

Fair enough. As Mr Suzuki walked around the function halls of this big flashy hotel complex in Boca Raton, an all-American pink palace of a place, his engineers and marketeers would bow as he passed. It’s a fascinating culture. They’ve given their new engine a Japanese nickname, which is etched on each unit in kanji script. It’s called Geki (parting seas) – a force to match the power of nature and the sea.

Does the performance match the hype? Let’s jump straight on board one of the test boats with a four-engine set-up. In a nutshell: formidable power and acceleration, and a gorgeous noise at full chat doing 65 knots. These are magnificent machines.

Piero Formenti, head of the Italian Formenti RIB boatbuilders, gave our test boats and engines the best run he could. He didn’t hold back. In true Italian fashion he took us to max speed, hammering corners like he was a Roman taxi driver given a Ferrari for an hour. I asked him for an opinion, and this is what he said: ‘These engines are amazing. Very stable. You have power when you need, they take the curves smoothly, fantastic. I think they’ll have a big impact and success for bigger RIBs. The power from zero is impressive.’

There were no RIBs to test, unfortunately, something that your esteemed editor will get into when they arrive in the UK, but George Cheeseman, head of Suzuki Marine in the UK, says that these new outboards will be in the UK for testing on the water at the Southampton Boat Show in September and available to customers in December/January. ‘We are taking orders now,’ he added. And I’m afraid the big question of price will be announced in September too.

Back to the exhibition halls, and David Greenwood, Suzuki’s American Product Manager, explained that this engine really did start with a blank sheet of paper. It’s not a modified version of another model. ‘This is the largest V6 outboard motor on the market today. The key features are the new dual-prop system, where the rotational forces counter themselves out, letting the boat track level, dual injectors per cylinder, variable valve timing and a dual air intake system. It’s a 4.4-litre block, which is making 80 horsepower per litre.’

I noticed the low speed manoeuvrability around the dock was good. Whatever the science is behind counterrotating props, and it’s complex, they make reversing much smoother with more grip. Parking just got easier.

As first impressions go, and I’ve spent 20 years filming boat racing from RIBs with engines good to terrible (and drivers to match), these Suzuki 350s are superb. Every journalist and boatbuilder I spoke to agreed. Suzuki Marine have a hit on their clever, long-term, innovative and technically brilliant hands.

The DF350A



At 350 horsepower, this V6 4-stroke is the largest, most powerful outboard Suzuki have built to date. In development for more than three years, it represents a significant milestone for Suzuki in both engineering and design.

350 horsepower and a 12.0:1 compression ratio

The robust engine displacement of 4.4 litres is matched by a high-performance 12.0:1 compression ratio, the highest ever for a production outboard engine. And we’re told that a unique combination of cool air intake, dual fuel injectors and a strengthening of the pistons is to be commended for virtually eliminating engine knock, a typical by-product of high-compression engines.

Suzuki Dual Louver System, direct air intake

At the launch event in Florida, we heard from Suzuki’s engineers about how they have taken a step forward by designing an air intake system that allows the engine to draw in ample fresh air, while separating out water, spray and moisture. Dual louvers under the hood trap larger water droplets and then moisture as it enters the engine cowling, resulting in zero water intake during testing. In addition, intake air temperatures are, on average, 10º cooler than ambient, providing the combustion chamber with cooler, denser air for a more powerful cycle.

Dual injectors

Two smaller fuel injectors for each cylinder allow for precise injection of fuel to the centre of the combustion chamber, which avoids off-centre 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.

Advanced piston technology

To achieve 350 horsepower, the surface of the piston needs to withstand added forces. And in order to ensure 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. The connecting rods and hardware have also been strengthened to handle the added loads.

Suzuki dual-prop system

While counterrotating propellers are not a new technology, they have never been successfully used on outboard motors, until now. Mark Beeley, Suzuki GB’s Area Sales Manager, explained that 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 gear case is kept to a minimum, which in turn allows for the design of a sleeker, more hydrodynamic gear case.’ He added: ‘Our engineers spent many hours in computer simulation and on the water, knowing that reducing drag underwater would be essential to improving overall boat speed and performance.’

The counterrotating propellers also provide added surface area, which appears to add more stability and increased ‘traction’ or grip underwater (think of the wide slicks on a drag racer as compared to typical tyres). This results in exceptional acceleration, or hole shot, truer directional propulsion (eliminating steering torque), better-than-expected top speeds and incredible reverse thrust. Importantly, we’re told that these benefits are apparent even on heavier boats with full loads of fuel, gear and people.

Proven Suzuki technology

Like Suzuki’s other V6 outboards, the DF350A features its own offset drive shaft 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. (It is worth noting that the DF350A can be mounted 27″ on centre, so it will fit on more transoms, and take up less space in twin, triple and quad installations.)

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. Like all Suzuki 4-stroke outboards, the DF350A is extraordinarily quiet at idle.

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