Yamaha 4.2L V6
4-Stroke Offshore Outboard
Faster Than a 2-Stroke Outboard?
Yamaha Outboard's family of V6 offshore outboard motors are 246 pounds lighter than the V8 F300 it replaces and they weigh 51 pounds less than the previous generation V6 F250. That means the 4.2-liter F300 qualifies as the lightest outboard in its class paying big dividends in performance and vastly improved fuel economy. So how did Yamaha Outboards do it?
The horsepower boost was easy. The big-bore 4.2-liter breathes deeper than its predecessor thanks to a new throttle valve that measure a 13-percent wider bore (75 mm) than the previous 3.3-liter four-stroke Yamaha. Intake valves measure 14-percent wider, while exhaust valves are 10-percent bigger. Air flow is voluminous. Camshaft timing is variable (electro-mechanical). Intake tracks have been lengthened for substantially stronger low-end torque. Yamaha's proprietary In Bank Exhaust system is renowned for the way it minimizes back pressure to pump up performance.
Beyond raw, bloody horsepower, the real question is exactly how did the engineers trim so many pounds from the savage beast? The answer is new materials and processes. The build specs include plasma-fused sleeveless cylinders instead of conventional steel liners set in an aluminum block. Plasma-fused simply means an alloy dust, comprised of chrome, nickel, manganese and other elements, is super-heated in a plasma process and fused to the cylinder wall. Plasma fusion cuts 6.2 pounds of weight off the cylinder block and makes room for 2 mm wider cylinder bore (Bore and stroke build cubic inch displacement).
A real eyebrow raiser: This plasma fusion coating is 60 percent harder than mere steel and is very wear resistant. To the naked eye the plasma surface looks as smooth as glass, but it's micro-dimpled. Its micro-texture surface (like the dimples on a golf ball} better holds oil, reducing both wear and friction, which pays big dividends by way of a horsepower boost and better fuel economy. According to Yamaha Outboards, because the pistons pump up and down more freely, fuel economy measures 17-percent better than the nearest competitor.
Also important to note, plasma fusion shrinks powerhead weight because the cylinder walls take up less space in the engine block than a conventional steel sleeve. Naturally it follows, that frees-up room for wider-diameter pistons. In other words, there's more displacement shoehorned into the same space. Another plus, with plasma fusion, waste heat transfers more efficiently between the cylinder walls and the cooling system.
Weight saving measures include a lightweight composite oil pan that's 61 percent lighter than its aluminum counterpart. Being composite, a sheet molded compound, it doesn't corrode.
Alternator output registers a whopping 70 amps, versus the previous Yamaha outboard's still ample 45 amps. And depending on whose numbers you crunch, that's 22 percent higher net amperage than the competitors. In spite of greater electrical output, the new alternator weighs six pounds less. I really like the new shift-dampener propeller hub system that reduces the loud clunk often heard on larger outboards when shifting into gear.
Yamaha Customer Outboard Protection, or YCOP for short, talks to the outboard's Electronic Control Module (ECM) rendering the Yamaha outboard unable to start without its electronic key fob. Theft becomes difficult with this highly water resistant key fob that electronically arm and disarm the system.
These offshore outboards are clean, boasting a three-star rating for ultra-low emissions from the California Air Resources board (C.A.R.B.) and meet, or exceed, all Federal exhaust emissions requirements.
As for rigging, Yamaha outboards are compatible with Command Link Plus, a high-contrast color LCD screen displays outboard motor, boat and other vital functions on its five-inch screen. Multi-function Command Link Plus reduces the space that would otherwise be taken up on the console by multiple gauges.
The offshore outboard's control boxes feature push-button starting and stop buttons. The one-key operation controls up to three outboards with Quad engines using individual key switches. Start/stop panel lights indicate when outboards are running. The All Engine start/stop button allows multiple engines to be started one at a time, preventing high amperage current draw on the starting battery.
Finally, the new generation Yamaha outboards are available in both 25- and 30-inch shaft lengths as well as left and right-hand rotation.
VIDEO: Yamaha's Dale Barnes discusses the merits of Offshore V6 technology.
|225 @ 5500
250 @ 5500
300 @ 5500
|Operating Range (rpm)||5000-6000 rpm|
|Cylinder Block Configuration||60-degree V6|
|Alternator (amps)||70 amps|
||1.75 to 1|
|Bore x Stroke||3.78" x 3.78"|
|Compression ratio||10.3 to 1|