Lighter engines, bigger bangs

Chris Beattie | VOLUME 25, ISSUE 4
The low weight is primarily accomplished by the use of new materials.
It’s all about size, according to Yamaha, which recently released its new range of Offshore V6 outboards.

The bigger the piston, the bigger the bang is a time-honoured maxim amongst engine designers the world over. And it’s a sentiment obviously taken to heart by engineers from the world’s largest manufacturer of outboard engines, judging by the recent launch of Yamaha’s new generation Offshore range of V6 powerplants. Fundamental to the new design is a large-capacity, low-weight package that delivers impressive power and, most importantly, broad reserves of torque.

Comprising the F300, F250 and F225 4.2lt four-stroke engines, the new outboards share the same basic architecture based on a new high-tech, lightweight V6 platform utilising a high-performance, double overhead camshaft, four-valve layout.

Presenters at the launch, conducted on the Gold Coast in late June, emphasised the efforts engineers have gone to in order to save weight without sacrificing strength in the new powerplants. In fact, at 253kg, the F300 is a whopping 112kg lighter than the V8 engine it replaces, while the F250 and F225 tip the scales up to 23kg less than previous Yamaha V6 four-strokes of comparable horsepower.

The low weight is primarily accomplished by the use of new materials, including a special advanced polymer composite lower engine pan and a new thermally-applied plasma fusion coating for the cylinder walls in place of more conventional – and much heavier – steel cylinder liners.

Other new features shared across the platform include Yamaha’s Variable Camshaft Timing system for improved low-and mid-range power and throttle response, a claimed up to 17 per cent improvement in long-range fuel economy over comparable 300hp engines for the F300, a more powerful 70-amp alternator, High Definition Gauges and Digital Electronic Controls, a Long Span engine mounting system and a patented shift dampener propeller hub system for smoother, quieter shifting.

At 4.2lt, the new engines boast comparatively large capacity for their output, which Yamaha says was a deliberate ploy aimed at generating more torque, resulting in less time to plane and better throttle response.

On the water, it was easy to see and feel the improvements.

Shifting from forward to reverse was much smoother and quieter than I’m used to and low-range pulling power was very impressive. This was, perhaps, best demonstrated on a CruiseCraft Resort6 powered by a F225 engine. This is a craft that might occasionally be seen towing skiers – a task that would normally see a high-torque two-stroke powerplant bolted to the transom. But in this application, the F225 four-stroke produced impressive amounts of stump-pulling grunt from way down low and would, I’m sure, be a worthy tow-sport powerplant.

I was particularly keen to sample the flagship F300 engine, which, for the launch, was attached to the transom of a CruiseCraft Explorer 6.85.

Power and acceleration out of the hole was very impressive on such a large boat and I was also taken with how quickly it came on to plane. In this particular application – a typical offshore fishing rig – the F300 delivers good speed for getting out to the grounds and back quickly, while also achieving good fuel economy for its size. According to Yamaha’s own figures, on this particular application it achieved an average maximum speed of 44 knots (81.65km/h), while delivering best cruising fuel consumption of 1.39km/lt at 3500rpm. This works out to a range of 409km – pretty good for a boat of this size.

From our brief test run, I predict Yamaha’s new Offshore range of large-capacity four-strokes will end up on the transoms of plenty of boaties who are looking for a combination of torque, low weight and fuel economy, while also delivering low emissions.

Recommended retail pricing runs from $25,797 for the F225FETX to $32,612 for the range-topping FL300BETC.

For more information, talk to your nearest Yamaha dealer or go to: