Due for release later this year are Yamaha’s new V6 four-stroke F300,F250 and F225 outboards, based around a newly developed 4.2L 60 degree V6 engine – the accompanying exclusive images of these new outboards were sourced directly from the US.
By using a highly-advanced thermally-applied plasma fusion process on the cylinder walls, Yamaha says its new V6 Offshore outboards now have cylinder walls that are 60 per cent harder than steel, meaning larger cylinder bores for increased displacement, resulting in more power and torque without increasing outer cylinder dimensions.
This also means a dramatically lighter weight. All three new models in this range claim to weigh less than Yamaha’s current 3.3 litre F225, far lighter than any competing four stroke model. Weight is now comparable to direct injected two strokes but the new range offers substantially larger capacity.
The new F70 is a further development of the F60, sharing the same displacement and stroke. According to Yamaha the engine is lighter than any competitive four-stroke, or direct injected two-stroke motor in the 70–75 horsepower class. The F70 achieves this by its unique four valves per cylinder design activated by a single overhead camshaft rather than the conventional dual camshaft design for 16 valve engines. This reduces the weight that would result from having an extra camshaft and the components that go with it.
Four valves per cylinder have dramatically increased this engines volumetric efficiency – the efficiency with which the engine can draw fuel and air in and push exhaust out of the cylinders. Increasing this efficiency means the F70 is able to run at a higher rpm with the maximum operating RPM increased to 6300rpm. The resulting top end performance should be great for boaters who want to get to their favourite spot first.
More info on Yamaha’s new outboards here.
