OVER the last few years there has been a rapid awareness in the benefits of four-stroke outboards and fuel injected two-strokes. While there was once only a very limited range in these engines, consumer demands and environmental demands to produce cleaner and economical engines has led to an increase in the range of engines available.
Until very recently there have been a few ‘holes’ in the range of engines available in the mid and top end horsepower. With the release of two brand new engines Yamaha now has a comprehensive range of outboards available.
Of most interest to anglers and families is the new 150hp four-stroke. This size engine provides the perfect partner for boats from 5.5m to 6.5m. Due to the new design there’s no longer a weight problem as the engine is virtually the same weight as its two-stroke counterpart, thus opening up the field for twin four-stroke rigs for those who want power, performance and economy without sacrificing the weight factor. The new F150A weighs 220kg, the Z150 two-stroke (high pressure direct injection) weighs 222kg and your standard 150hp carburetted two-stroke weighs 200kg (all dry weights).
Unlike the fuel injected and carburetted two-stroke engines, which are a V6 block, the F150A is a four-cylinder engine yet its output at the prop is 110.3kW at 5500rpm. This is the same as both of the two-strokes.
Yamaha recently matched the F150A up to a variety of different boats so boating writers could feel and drive these engines on varying hulls. The engines were fitted to the Seafarer Victory 6.0m, Mustang Bluewater 2000, Cruisecraft 5.5m bow rider and the Freedom Mirage 6.0m bow rider. There was also a 6.8m Haines Hunter Patriot with the new Z300hp fitted to it.
I doubt that there was a journo there who wasn’t impressed by the power range of these engines. Some four-strokes have been said to have flat spots at various revs, but not so in this case. No matter what speed you’re sitting at, apply a bit more throttle and there’s the power and speed to match. The boats had varying loads in them so it wasn’t as though the results were being taken from empty boats.
It’s not just top end speeds that need to be considered either – slow and idle speeds were ultra-smooth with little engine noise. It’s the quiet fume-free running that’s just as important as fuel economy when it comes to family boating. So many times we see families new to boating put off by the smell of oil and engine fumes, as found in many standard two-stroke engines.
If you’re a bit of a rev head, the 300hp fuel injected two-stroke will make the eyes water in the best of you. Even in the big Haines Hunter Patriot, the big V6 block with its 220.7 kW was no slouch. It’s not that heavy either at 257kg. Imagine that on a ski boat!
Both engines will be in stock this month. I predict that you’ll start to see a lot of offshore boats fitted with these engines, where big savings can be made with the savings on fuel and oil.
Make/model – Yamaha F150 A
Engine type – 4-stroke, 16 valve DOHC, direct action inline 4
Displacement – 2670cm3
Bore x stroke – 94.0mm x 96.2mm
Prop. shaft output – 110.3 kW at 5500 rpm
Idle engine speed – 700rpm +/- 50 (trolling 650 +/- 50)
Compression ratio – 9.0
Fuel system – electronic fuel injected
Max fuel consumption – 55.8L/hr at 6000rpm
Fuel – unleaded regular
Oil tank capacity – 5.2 l
Alternator – 12V - 35 amp
Exhaust – through prop hub
Weight – L 216kg X 220 kg (dry weight)
1) Yamaha’s new F150 four-stroke will have no problems finding a home on the back of both pleasure and fishing boats.