350 hp at 5,500 rpm isn’t bad. For an outboard motor, however, those numbers are remarkable. But that’s what Yamaha Motor Corp., U.S.A. Marine Group (Kennesaw, GA; www.yamahaoutboards.com) has developed. And it happens to be the first-ever V8 in the outboard industry. That 350 hp, by the way, is the output at the propeller.
According to Phil Dyskow, Yamaha Marine Group president, “No outboard manufacturer has ever designed anything even close to a 5.3-liter, four-stroke V8. Extra displacement helps provide what big boats need most—thrust. At the same time, displacement means the engine makes 350 horsepower without the strain and internal pressures found in high-output, small displacement engines.” The engine is a 60° V8 with four valves per cylinder and dual overhead cams. There is variable camshaft timing and multi-point fuel injection. The induction system has eight long intake tracks to optimize power. There is a system (“In-Bank Exhaust with Dual Power Surge Chambers”) to relieve pressure in the exhaust ports. The block is an aluminum alloy. To protect it from corrosion, Yamaha paints it with an exclusive process.
So why, you might be wondering, is a magazine with the word automotive in its title, writing about a boat engine? Well, as some of you may recall, Yamaha made another V8 engine, this one a bit smaller than that of the F350: a 3.4-liter engine. The horsepower of that earlier V8 was lower: 235 hp. That engine was used in the 1996 Ford Taurus SHO. Although that engine had its run between ’96 and ’99, Yamaha builds another version, a 4.4-liter V8, that’s used in the Volvo XC90 and the S80 (built to Volvo’s design specs).