350 reasons for serious consideration
05 December 2017
Freakishly fast, big displacement DF350A four-stroke stokes ambitions of Suzuki on both sides of the Tasman. So, you think you’ve seen it all before? Be assured that you haven’t. Suzuki’s new big boy on the block, the DF350A, unveiled to New Zealand Fishing World at a recent Noosa-based media day, certainly caught us by surprise.
Freakishly fast and exceptionally sticky are descriptions that come immediately to mind. That a pair of the 350 horsepower, V6 contra-rotating beasts nearly put our very qualified but embarrassed cameraman in the drink, complete with all his videography gear, underlines the respect passengers and drivers need to offer these units.
A physical manifestation of the speed experience is that at full throttle the 350s produce a fog, rather than the usual hose-like spray. It’s patently apparent that a lot of water is being moved in a very efficient manner.
To experience such a combination of immediate bite and g-force inducing acceleration was a first for us, as it was for most the attending media and Suzuki dealers on site.
Run speeds of 55 knots were delivered with regular monotony, despite the comparatively heavy loading of the boats. And there’s much more to the story than teeth-gritting acceleration and straight-line speed.
The prop stability in hard corners delivered a compelling argument for Suzuki offering something more than a little exciting for big boat enthusiasts, but more about the technology behind that observation later.
History of fast
Suzuki aficionados would not be surprised to see such impressive weaponry emerging from the respected Japanese innovator. The company has a long history of high horsepower four-stroke firsts.
Suzuki launched the first fuel injected four-stroke outboard in 1997, the first 250 horsepower four-stroke in 2003 and the first 300 horsepower four-stroke outboard in 2006.
While the 350-horsepower iteration is not a first, it was developed in Suzuki’s words, “from a blank sheet of paper” and as such offers several technological improvements designed to deliver “fast with efficient” that will surprise many educated readers.
Compression the solution
The DF350A features 4.4 litres of displacement; said to be the largest for a V6 outboard on the market. At the same time, Suzuki increased the engine’s compression ratio to 12.0:1, also offered as the highest compression ratio for a production outboard to date.
Making this combination work in the real world required a focus on optimal fuel burn conditions within the block. Cool, dry air delivery became a priority.
The DF350A’s new direct intake and dual louver system works by converting water vapour to particles, which are deflected out of the intake flow by a network of louvres and blades configured in a dog’s leg shape. The result is claimed to be a moisture-free flow of air no higher than 10 degrees above ambient.
Other internal hardware developments of note include a new dual injector system for precise fuel delivery and optimised cylinder cooling, and a piston design featuring shot preening; a technique said to facilitate more even pressure distribution within the chamber.
What’s all the fuss about contra-rotating props?
Well, in a nutshell, it’s about driving all that efficiently produced horsepower straight out the back of the boat instead of wasting it in the rotational forces of a spinning propeller.
There are also significant improvements in grip, as we noted in the insane corner handling. In the real world, this should be realised as additional thrust and steering stability when things get challenging, such as crossing bars.
Interestingly, the Suzuki engineers point out improvements laymen like us are unlikely to have thought of at first glance.
The two-propeller configuration of the contra-rotating system has allowed for opportune hydrodynamic improvements to the unit’s leg and prop foot.
Contra-rotating propellers allow for a wider distribution of engine torque across the total blade area while decreasing the forward-facing diameter of the blade, thus reducing drag.
To be fair, the physics is well over our fisherman's heads, but the more evenly distributed torque allows for a condensed gearbox diameter and hydrodynamic improvements of a thinner prop foot.
Frankly, we left this open day with the Suzuki DF350A thoroughly impressed and excited by what such an all-round high performing product could offer demanding New Zealand boaters.
Yes, the hole-shot and grip offer an experience high speed enthusiasts like water-skiers will appreciate but make no mistake, if this 350-horsepower big displacement transom rocket delivers on the potential we saw, it’s going to turn heads in the serious offshore fraternity quick smart.
Fast, fuel efficient, highly intelligent and just so damn good looking. That’s quite a package.
Visit Suzukimarine.com.au for a further fill on the new DF350A
Still to come
If that’s where you think this story ends, think again. Next week we’ll look at the fingertip technology harnessing this new beast. And should have a video to share, if the cameraman succeeded in keeping this speeding bullet in the frame.