MIAMI, 1pm Feb.15, 2007 — In a dramatic cloke and dagger/dog and pony show, Yamaha Marine unveiled the boating industry’s first V8 5.3-liter, four-stroke outboard motor today at the Miami Boat Show. The Yamaha F350. produces 350 prop-shaft rated horsepower, and it is designed to provide massive thrust for the heaviest off-shore outboard-powered boats and outboard-powered boats the industry.

The rumor around the Yamaha booth was that at 5.4 ltrs, there are enough cubic inches in this engine to put out as much as 500 hp (some said more) in the coming years.

The Yamaha F350 provides up to 45 percent more thrust than 250-hp class outboards. The company’s first V8 outboard powerhead was designed specifically for the marine market and features more than 600 new parts. The design is a 60-degree V8 with 32 valves (four valves per cylinder) and double overhead cams. It uses variable camshaft timing to optimize the engine’s torque at low and mid-range rpm. With sequential, multi-point fuel injection, it has eight long intake tracks in the induction system to optimize power. In addition, it features In-Bank Exhaust with Dual Power Surge Chambers, a system that relieves pressure in the exhaust ports.

The F350 was designed from the beginning to power off-shore boats. However, it employs a number of new features designed to even further enhance its capabilities. A component of the UCP-II Ultimate Corrosion Protection System is an industry exclusive paint process for the proprietary Yamaha aluminum alloy engine block. It combats corrosion both inside and out, protecting the cooling passages and other key components. In addition, the outboard uses an “Ultra-Tough” gear case with dual water inlets for improved cooling. Inside the lower unit are hardened gears and enhanced bearings and surfaces for greater off-shore durability. Forged motor mounts and an oversized mounting bracket (with 6 transom thru bolts) also add to the F350’s portfolio of toughness.

The 3 blade SS prop looked to be about 16 inches in diameter, remenescent of the big Suzuki 3 blade
Yamaha plans to begin deliveries to boat builder and dealer partners by summer 2007.
Yamaha also unveiled a new electronic shifter capable of handling up to 3 engines. This shifter has a kinky, ie. "neat" trolling feature that with each push of a button on the new electronic tach, allows trolling speeds to be increased from 600 rpms by 50 rpms with each push of the button, up to 1000 rpms without touching the throttle.
Yamaha had a working model of the new 350 on display in their booth, and it did not look that much bigger than the Suzuki 300.

Curtesy of Hull Truth Boating Forum: