Yamaha introduces the newly designed F350 outboard engine.
There’s more than just a powerful look to Yamaha’s new F350 4.3L V6 Offshore outboard. It’s a design masterpiece with innovative features in the cowling, in the machinery, and down in the prop. Yamaha’s continued advances for its outboards have all landed in the F350, as well as having a few of its own, which offer boat owners more power and performance for offshore reliability and inshore maneuverability.
“The V-six three-fifty is based off of the four-point-two-liter platform, which is the two-fifty and three-hundred,” says Yamaha’s Capt. Sean Gill. “They beefed up the lower unit by adding more teeth to it, so it’s a stronger lower unit. They added what we call the enhanced reverse thrust, which is below two-thousand rpms; all of the exhaust gases don’t come out of the hub, they exit from above, so you’re backing up into clean water, which is great. The integrated digital steering, or electric steering, actually gives you a little bit farther sweep of the motor, about two degrees farther, and it’s much more responsive.”
The F350 has big power using larger intake and exhaust valves than the F300, but uses the same diameter electronic throttle valve as the 5.6L V8 XTO 450 outboard. The Yamaha “Hot Sheet” explains that the engine’s improved camshaft creates higher valve lift for longer opening duration for both intake and exhaust, while newly designed valve lifters create valve clearance to achieve boosted combustion. The arrangement maximizes air movement for better air flow, thus, more power. Add to that a new crankshaft with a longer stroke for more torque at lower speeds and a more responsive performance due to the mapped fuel and ignition timing matched with the throttle movement.
“They increased the compression from ten to eleven on this engine,” says Gill.
With an 11:1 compression ratio, the F350 manages air displacement through redesigned intake manifolds equipped with 40 percent larger surge tanks (compared to the F300). The port and starboard intake manifolds are identical to enable a centerline placement for the electronic throttle valve that is eight percent larger than the F300 throttle valve for smooth air flow and responsive power.
The F350 also takes the same water sensor from the XTO 450 to control overheating by detecting increasing engine temps sooner than traditional sensors, a more durable solution. The sensor monitors the temperature of the cooling water instead of the block. An intake silencer provides a sound buffer for the increased air flow to the head, and a larger oil cooler capacity helps reduce friction and distribute heat.
When it comes to efficiency of the prop, the new gearcase, with its added teeth, allows for a stronger torque transfer from the powerhead. It also incorporates Yamaha’s Thrust Enhancing Reverse Exhaust technology. What that does is keep the turbulence from the exhaust bubbles above the anti-ventilation plate and away from the propeller which, as Gill mentioned, means you back up into clean water. It’s designed to engage and produce high thrust at 2,500 rpms in reverse to give more precision when maneuvering around the docks or backing down on a fish.
Even the cowling has new features, such as the exhaust port with stator fan to help cool the mechanisms inside, especially at low rpms.
But one of the big reasons Gill admires this engine is the fuel economy. Anglers easily make 150- to 175-mile runs, and he’s seen up to a 15 percent reduction in fuel use.
“That equates to hundreds of gallons of fuel, time, and wear and tear on the engine,” says Gill. “When you get that power to torque and the weight ratio right, you can have a boat doing three thousand, eight hundred rpms at forty miles an hour (getting 1.9 miles per gallon). The engine isn’t working as hard to produce the same speeds, and it’s what this game is all about: fuel economy and boat control.”
Yamaha didn’t stop there. They introduced new pitch options for the Saltwater Series II propeller line, including right- and left-hand rotation and added new features to the Helm Master EX control. An integrated bow thruster control is available for single through quint outboard applications, and the Sleipner and VETUS bow thruster systems now work with the Helm Master EX joystick. The F350 links right into the Helm Master control and, as Gill explains, “with the digital platform, we’re full boat integration, digital integration. So we have the features, like the autopilot for example, the safest one in the world with deceleration mode. As I’m approaching the waypoint—you can set it for how far away, but I’ve got mine set for about a quarter mile—the boat will actually begin to reduce speed as you approach and then when you do, it’ll actually shift to neutral and you’ll just drift instead of run through it.”
Yamaha’s latest advancements along with the new F350 4.3L V6 Offshore outboard are impressive with the torque and even more so with the fuel economy. With additional features, such as the flush connection and TotalTilt technology, the F350 meets the demand for more horsepower, improved performance, and greater reliability in an outboard. yamahaoutboards.com
-by Steve Davis
