Yamaha Outboard 425-hp 5.6L V8

The new Yamaha 5.6L V8 XTO Offshore engine that was announced this week has a number of features which boaters should like, including direct fuel injection into the cylinder.

The engine was designed primarily to be used in large offshore boats for both fishing and cruising in multi-engine applications.

On Tuesday Yamaha announced its new 425-hp 5.6L V8 outboard.Yamaha Announces New 425-HP V8


Yamaha has a new lower-unit design that it says provides more thrust in reverse, something that big-game anglers will like when backing down on game fish.

Perhaps the most important aspect of the new Yamaha 5.6L V8 is the fact that it is the first 4-stroke marine outboard engine to have direct fuel injection into the cylinder. The Evinrude E-TEC G2 2-stroke has had direct fuel injection since its introduction in 2014, and the OptiMax 2-stroke engine, which was discontinued last week, also had direct injection. Yamaha says this will maximize power and efficiency in its new engine.

Working hand in hand with the direct fuel injection is a series of five fuel pumps that can vary the pressure of the fuel and create what Yamaha describes as “unprecedented fuel injection pressure of up to 2900 psi to maximize atomization and efficiency.”

Other design elements include an exhaust system on the inside of the V of the engine block so that the unit can have a slightly slimmer width, exhaust ports above the prop hub on the lower unit to help create up to 300% more reverse thrust than those on the Yamaha 350, a dual-chamber oil pump to ensure proper flow at all engine speeds, and what Yamaha calls a unique water-pump system utilizing a steel impeller that helps provide sufficient water volume and a “massive” rubber water impeller for high pressure and flow.

The new engine has a number of other features as well. No price was announced for the engine and the company says deliveries will start in the summer of 2018.

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