Engines — Elizabeth
Ginns Britten, Capt. Ken Kreisler, and Capt. Patrick Sciacca
2004 Engines Preview
Yamaha is introducing three new outboards, including a pair of High Pressure Direct Injected (HPDI) two-strokes and a 150-hp four-stroke. Billed as the world’s first 300-hp direct-injection outboard, the Z300 was designed for boats in the 30- to 40-foot range. Another version of the same engine, the VZ300, is designed for bass boats. Featuring a 3.3-liter, 204-cubic-inch, 76-degree V-block, these engines develop considerable low-end torque, necessary to power larger boats while providing fuel economy.
Sporting second-generation HPDI technology, the Z300 and VZ300 utilize a pair of high-pressure fuel pumps that, according to Yamaha, delivers fuel at an industry-high 1,000 psi. This provides extra atomization of the fuel-air mixture and, according to Yamaha, results in more complete combustion, better acceleration, and higher top speed. Other features include a water-cooled intake crankcase, a new exhaust-pressure reduction system, and a heat-treated crankshaft, connecting rods, and lower-unit gears that Yamaha says are more durable.
Also new on this engine is a special ion plating applied to the top piston ring. According to Yamaha, it provides better cylinder contact, resulting in as much as a 55-percent reduction of oil consumption compared with the typical two-stroke.
Yamaha’s HPDI features a fuel rail system that delivers the fuel to the top of the piston and, as fuel is not injected into the cylinder until the exhaust port is closed, results in minimal preburn fuel charge escape. An ECM constantly analyzes data and automatically adjusts vital parameters for maximum engine performance and fuel efficiency, and at idle the engines fire on only four cylinders to save fuel and prevent carbon buildup. Both the Z300 and VZ300 exceed 2006 EPA emission requirements and have a two-star CARB rating for very low emissions.
On the four-stroke side, Yamaha has introduced a new 150-hp model. Using a lightweight, in-line, four-cylinder powerhead, it weighs just 466 pounds and features forged pistons; a heat-treated crankshaft, gears, and connecting rods; a flywheel damper to reduce vibration; and water-sealed outer walls to reduce engine noise.
Yamaha’s Crossfire Valve System, a double-overhead cam design featuring four valves per cylinder, provides clean combustion thanks to a blow-by gas reburning system that removes unburned fuel from the exhaust and routes it back into the fuel delivery system. The entire system is overseen by an ECM that ensures a precise fuel-air mixture and includes a warning system for overheat, over-rev, and low oil pressure, plus a neutral throttle limiter and start-in-gear prevention sensors.
The F150 exceeds 2006 EPA standards as well as the 2008 CARB emission standards and has a three-star ultra-low-emissions rating.
Yamaha Phone: (800) 88-YAMAHA. www.yamaha-motor.com.
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This article originally appeared in the December 2003 issue of Power & Motoryacht magazine.