You want a bigger outboard? You’ve got it! Yamaha has introduced the F425 XTO Offshore V8 outboard, eclipsing the Yamaha F350C as this engine manufacturer’s biggest offering on the water. This engine should be made available at any time soon (It should hit the water “during the summer of 2018,”) and we’ve learned some details that motor-heads will find interesting.
The Yamaha F425 XTO in action.
Weight: The engine weighs in at 952 pounds with a 25 inch shaft and 999 pounds with a 35 inch shaft. That makes it about 200 pounds heavier than the F350C and almost 300 pounds heavier than the Mercury Racing Verado 400R. As with some other Yamaha offerings, weight is kept down with the application of high-tech plasma-fused cylinder walls. These eliminate the need for heavy stainless-steel cylinder sleeves, and Yamaha says they’re also stronger that traditional sleeves.
Displacement: The F425 XTO is a naturally-aspirated, direct fuel injected four-stroke V-8, which displaces 339.23 CID. Although direct-injection has been used in automotive applications with four-stroke motors, this is the first direct-injected four-stroke outboard to hit the market. The engine utilizes five separate fuel pumps to drive 2,900 psi at the injectors!
Performance: Triple F425 XTO outboards have pushed a Contender 39 to a top-end of 72.5 MPH. On the monstrous Grady-White Canyon 456, top-end hit 55.5. We’re happy that unlike some high-horsepower outboards, the F425 XTO can run on 89 octane fuel. (The company says premium is recommended for maximum performance).
Perks: Yamaha has designed a new line of props to match up with these outboards, to take advantage of the massive amount of torque they create. These go up to 17.125 inches. An unusual feature is an exhaust cut-off that kicks in when you shift into reverse. It re-routs the exhaust so it doesn’t flow through the hub. This prevents the exhaust gas bubbles from running across the propeller blades (which happens in all other outboards with through-hub exhaust) and improves the propeller’s bite in reverse. Finally, Yamaha also developed a integrated electric steering system. This eliminates many of the cables and hydraulic lines that previous rigging required.
Want to learn more? A visit to Yamaha is in order.