Yamaha 350 HP V8
Monster Motor Outboard
The World's First 350-Horsepower Outboard Motor:
A 5.3 Liter 4-Stroke V8 Outboard
Yamaha Marine was first with the most potent, production outboard motor ever built, the F350, a 5.3 liter, 350 horsepower V-8. Why so much horsepower? Outboards are growing more muscular because boat builders asked engine companies to up-size motors, to make them powerful enough to lend mega zoom to 38-foot center console boats and beyond. The reason why is as simple as the sea is salt.
Maximum motors work magic with big boat multiple installations. Twin or triple engines cost less to purchase and maintain and burn less fuel than triple or quad installation. With one fewer gear case dragging in the water top speed and acceleration skyrocket. So while bigger is undeniably better, the real epiphany comes with the realization that fewer motors work smarter not harder. For these reasons Yamaha Marine's spanking new F350s would find a happy home on any big boat transom. Look for near term introduction of F350 class boats from Edgewater, Grady White, Pursuit and other boat builder partners that collaborated with Yamaha.
Beyond raw, bloody, horsepower the Yamaha F350 325 cid four-stroke boasts a startling number of tantalizing new technologies, things like ionic combustion sensors that constantly monitor fuel burn and adjust spark timing accordingly; Dimpled outer cylinder sleeves reduce oil consumption. New-generation head gaskets lock in horsepower; And updated corrosion protection fights the ravages of saltwater inside cooling passages and on external components parts. Curb weight is an acceptable 804 pounds.
Several years in research, development and prototyping, it was designed from the proverbial blank page. Restated for emphasis: Contrary to what you may hear from some self-pronounced experts dockside and on online boater forums, this engine was NOT derived from an automotive engine block. Instead, it was designed specifically to be an outboard motor and features more than 600 new parts. Even though Yamaha is renowned for the V-8 car engines it built for Ford, the new Japanese outboard is pure marine motor.'
Its 325 Cubic Inch Displacement aluminum block is a 60-degree-V. Cylinder heads are populated with 32 valves (four per cylinder) opened and closed by double overhead camshafts. Yamaha's F350 takes advantage of a number of interesting technologies: Ionic combustion chamber sensors constantly monitor the burn and adjust spark timing accordingly; a dimpled outer cylinder sleeve reduce oil consumption; Yamaha's Enhanced Ultimate Corrosion Protection System boasts additional sacrificial anodes along with an innovative internal paint process. Yamaha's Command Link Digital Electronic Control system has redundant electronic engine control, automatic multi-engine synchronization and electronic throttle and shift.
The two cylinder banks are arrayed in a 60-degree V with 32 valves (four valves per cylinder) and Double Over Head Camshafts. Variable camshaft timing optimizes engine torque at low and mid-range rpm, precisely the rpm band where boat motors log the majority of engine hours. Sequential, multi-point fuel injection pours on the fuel in precise spurts.
Technophiles will rub their hands together in glee when they learn about the eight, long intake tracks flowing a massive volume of air into the combustion chambers and how special chambers relieve exhaust pressure. Translation: Not a drop of horsepower is squandered. Naturally, throttle and shift controls are electronic, with automatic, multi-engine synchronization. Twin and triple installations are the rule for now, quad commandos have to wait a spell.
One of the biggest engineering challenges in building an outboard motor packing a 350-horsepower wallop is designing a gear case robust enough to stand up to the massive torque. Confidential sources whisper from the shadows that competing brands of maximum horsepower outboards are waiting in the wings as engineers learn special methods for keeping pinion gears from stripping their teeth. So it should come as no surprise to learn that the Yamaha F350 already features hardened gears and ultra heavy-duty bearings for maximum durability. Even motor mounts are forged and the mount bracket oversize.
|Configuration||60 degree V8 DOHC 32-valve|
325 Cubic Inch
|Bore x Stroke (Inches)||3.70 x 3.78|
|Compression Ratio||9.6 to 1|
|Propshaft Horsepower||350 @ 5500 rpm|
|Wide-Open-Throttle Operating Range||5000-6000 rpm|
(Minimum Pump Octane 89)
10% Maximum Ethanol
(40A @ 1000rpm)
|Gear Ratio||1.73 to 1|
|Limited Warranty||3-Year Pleasure
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