Marine Engine Digest

Free Information About Gas and Diesel Outboards, Stern Drives and Inboards



 

Yamaha 350 HP Monster Motor

 

Introducing the world's first 350 horsepower outboard motor, a 5.3L  four-stroke  V-8.

Yamaha Marine has introduced the most potent, production outboard motor ever, the F350, a 5.3L, 350 horsepower V-8. Why so much horsepower? Outboards are growing more muscular because a couple of years ago 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.

 

Even though Yamaha is renowned for the V-8 car engines it built for Ford, the new Japanese outboard is pure marine motor. Several years in the making, it was designed from the proverbial blank page. Its 325 CID aluminum block is a 60-degree V. Cylinder heads are populated with 32 valves (four per cylinder) opened and closed by double overhead camshafts. Cognoscenti already know variable cam timing optimizes torque at low and mid-range, exactly the rpm 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 chamber 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 hp 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 Uber 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 the Yamaha F350 features hardened gears and ultra heavy-duty bearings for maximum durability. Even motor mounts are forged and the mount bracket oversize. © Copyright 2007  by Tim Banse

 

Block configuration

V-8 60 degree

Displacement

5.3 Liter - 325 cid

Prop shaft horsepower

350 @ 5500 rpm

Cylinder heads

DOHC / 32 valve with Variable Camshaft Timing (VCT)

Compression

9.6:1

Full Throttle RPM range

5000 – 6000

Fuel induction

Sequential multi-point Electronic Fuel Injection

Fuel type

Regular Unleaded (Minimum Pump Octane 89)

Exhaust

In-bank dual exhaust with Power Surge Chambers

Intake

Electronic throttle valve with 8 individual long intake tracks

Ignition system

32-bit ECM with integrated coil-in-cap ignition design

Alternator Output

50A (40A @ 1000rpm)

Lubrication

Wet Sump

Gear ratio

1.73:1

Controls

Command LinkÆ - Digital Electronic Controls

Synchronization

Auto sync throttle control with twin and triple applications

Trolling throttle adjustment

+/- 50 rpm increments (600 - 1000 rpm range)

Weight

25" shaft / 804 lbs

C.A.R.B.

3 – Star Rating

Limited Warranty

3-Year Pleasure, 3-Year Government, 1-Year Commercial

 

 

For more outboard motor stories:

 

  Marine Engine Digest Home Page

 

 

 

Yamaha Marine's F350:World's first 350 horsepower outboard.

 

 

 

Yamaha Marine's F350 Propeller:

 

video: 1050 HP

 

Watch a 36 Open rigged with triple F-350 Yamahas smash and throw water.