Big Crazy V8 Power from Yamaha

New Yamaha 425 HP V8 Outboard

Yamaha Marine has officially unveiled the monstrous V8 XTO Offshore, a 425-horsepower, naturally aspirated 5.6L outboard.

The new engine is designed to push heavy offshore boats and yachts, further positioning the company as a supplier to the growing saltwater center console market.
yamaha 425 HP motor
“We’ve been working on this for a lot of years,” said Yamaha Marine Group President Ben Speciale during a product launch and marine industry media event Tuesday night in Chattanooga, Tenn.

The XTO Offshore is an entirely new platform for Yamaha, Speciale said.

Engine Details

The new engine, which will be start shipping in August, carries a five-year limited warranty for pleasure use and comes in three different shaft lengths – 25 inches, 30 inches and 35 inches.

When fitted with a propeller and filled with motor and gearcase oil, the 35-inch XTO weighs more than 1,000 pounds.

“This engine is designed to take us to the next level of what we can possibly do with outboard motors within the industry,” Speciale added. “We are answering the call for bigger boats with a different platform, a new, big-block 5.6L V8. It’s all about integrating power systems into much larger boats.”

Pushing the heaviest offshore boats and yachts requires driving large propellers, a massive, rugged gearcase and an extreme powerhead.

As the first four-stroke powerhead in the outboard industry to use direct injection, the XTO sprays fuel at high pressure directly into the combustion chamber, rather than the intake track, just before the intake valve.

This system features five fuel pumps and injection pressure up to 2900 PSI. The new engine has the highest compression ratio in an outboard – 12.2:1.

Carbon-coated shimless bucket-type valve lifters also increase durability, while a dual-chamber oil pump ensures proper oil flow and delivery.

Plasma fusion replaces conventional steel cylinder liners. The micro-textured surface is 60 percent harder than steel and significantly lighter, contributing to increased displacement without increasing powerhead size.

The resulting surface also increases fuel economy by decreasing internal friction.

Watch the Video Overview

New XTO OS propellers are made to complement the torque potential of the Yamaha V8 XTO Offshore. These new propellers produce more thrust in both forward and reverse, using diameters from 16 to 17 1/8 inches.

The XTO Offshore also has a two-stage water pump and dual chamber oil pump, each designed for heavy loads associated with high RPM operation.

Spark plugs made from iridium provide improved throttle response, economy, increased service life and improved power. The new V8 XTO Offshore also features quad thermostats, with two thermostats per cylinder bank, for improved flow and better regulation of engine and oil temperature.

“We doubled our quality standards on this engine,” Speciale said. “Here’s what I mean by that. If we were previously doing 200 hours of testing, we went to 400 hours. If we were doing 400 hours, we went to 800 hours. We spent a lot of money on fuel [testing this engine].”

The V8 XTO Offshore steering system has no hydraulic lines or linkages. The steering control unit receives electrical signals from a cylinder position sensor to carry out joystick and steering operation.

“This engine has a fully electric steering system,” Speciale said. “When you rig it, you plug in a harness.”

A new exhaust-gas relief system helps produce reverse thrust up to 300 percent of that developed by Yamaha’s F350.

“The reverse system on this engine allows the exhaust to be above the propeller when the engine is put into reverse,” Speciale said. “The prop grabs clean water.”

Boats powered by the V8 XTO Offshore need go no further than the dock for a lower unit service, thanks to a new gearcase lubricant exchange system that allows fluid change while the boat is still in the water.

The V8 XTO Offshore’s charging capabilities provide up to 90 amps of total (gross) power, reaching a peak net output around 1,500 RPM.

Yamaha’s Helm Master and the CL7 display have also been updated along with the launch of the new XTO Offshore outboard.

“Today’s boaters want to customize their boating applications to make their experiences on the water even more enjoyable,” Speciale said. “These new feature-rich offshore products give boaters more options and versatility when it comes to boat control, maneuverability and propulsion.”

The latest version of Helm Master includes the following updates:

  • In StayPoint or FishPoint modes, one forward, rearward or sideward bump of the joystick will move the boat’s position 10 feet; additional bumps within 3 seconds of each other will move it up to 100 feet total
  • In StayPoint or DriftPoint modes, one twist of the joystick will move the boat’s bow heading angle by 5 degrees; additional twists within 3 seconds of each other will rotate the boat by up to 50 degrees total
  • A new feature called Pattern Shift allows the operator to troll below standard in-gear trolling speed by shifting into or out of gear to meet a desired target speed. In calm water, resulting minimum speed can be less than 0.5 mph
  • Boaters can now adjust position and heading directly with the joystick. Prior versions required leaving a SetPoint mode, then adjusting, then re-activating the mode
  • The FishPoint High Mode RPM setting remains adjustable for fine tuning the power requirements for each individual vessel’s needs or to match conditions
  • The FishPoint center mode for quad engines now allows for quieter operation by using the center engines only for thrust and the outer for increased electrical charge output. The result is efficient, quiet charging.
  • Yamaha also announced it will offer a 35-inch shaft length model of the F300 4.2-liter Offshore V6 outboard, digital electronic control models only.


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    ABOUT Yamaha Motorsports®

    The Yamaha Motor Corporation is the second largest manufacturer of motorcycles in the world. Yamaha Motor Corporation owns its wholly-owned subsidiary in the U.S. called Yamaha Motor Corporation, USA, that handles not only motorcycles, but also snowmobiles, golf carts, outboard engines and water vehicles, under the brand name of Yamaha as well.