300r engines

4.6L V8
300R

Flex Some Muscle

Tuned up with Mercury Racing components to deliver blistering speed, the V8 4.6L 300R outboard delivers crisp throttle response, thrilling top-end power and confident control, the perfect match for a wide variety of high-performance boats. The 300R midsection and gearcase options, tie-bar and steering choices allow the creation of a near-custom configuration to provide optimal performance and ease of installation for most applications, including re-power upgrades.

Speed Boat
300r lifestyle
300r
300r
300r

A word from Mercury Racing

“Every performance powerboat enthusiast should experience the awesome punch of the Mercury Racing V8 300R outboard.”

Jeff Broman

Director, Mercury Racing Category

MIDSECTION OPTIONS

The Mercury Racing 300R outboard is offered with three midsection choices, each designed for specific performance applications.

Mid Section
Short Runner intake

Short Runner Intake

To extract maximum performance, the Racing 300R is equipped with a Mercury Racing-designed short-runner intake, high-performance intake camshafts, an oil cooler and a performance-optimized ECU calibration that increases the WOT range to 6400 RPM.

Mercury Racing Advanced MidSection

(Racing AMS) features heavy-duty guide plates, Digital Throttle and Shift (DTS) control and Mercury electro-hydraulic power steering, and optional integrated rear tie-bar brackets and Joystick Piloting for Outboards (JPO).

Mercury Racing Conventional MidSection

(CMS) features solid lower mounts, stiffer upper mounts and an integral Tri-Ram trim system and is available exclusively in a 20-inch shaft length with the Torque Master gearcase for tournament loaded bass boats, or the Sport Master gearcase for ultra-high speed bass or performance flats boats.

The Mercury Racing HD Conventional MidSection

(HD CMS) features heavy-duty forged transom brackets and a robust single-ram trim system with a remote pump, and optional rear tie-bar mounting plates and side steering brackets. Both the CMS and HD CMS are available with DTS or mechanical controls and Mercury electro-hydraulic power steering.

1/ 3
mid-section
cms
Ams HD
1/

gearcase options

Three gearcase options are available for the 300R outboard, each design for a specific high-performance application.

Gearcase Option
Tie-bar option

TIE-BAR OPTION

An optional rear tie-bar bracket integral to the Mercury Racing AMS provides a strong, ultra-light mounting point for precision steering in ultra-high-speed applications. Select HD CMS models are available with optional rear tie-bar mounting plates and side steering brackets for high speed applications when using the Sport Master gearcase.

Sport Master

The Sport Master gearcase offers heavy-duty durability for boats that travel in excess of 85 mph, with low-water pick-ups and a crescent leading-edge design that maximizes efficiency and speed.

5.44 HD

5.44 HD gearcase was designed and engineered by Mercury Racing for the most demanding offshore environments and features a larger 5.44″ diameter torpedo that provides extra lift for heavier boats. This is a highly durable gearcase for heavier center consoles, walkarounds, pontoons and deckboats.

Torque Master

The Torque Master gearcase is designed for heavier boats capable of hitting the 85 mph mark and features a heavy-duty 19-spline stainless steel propshaft.

1/ 3
Sport master
544 HD
Torquemaster
1/

Feel the power

The dual muffler system of Advanced Sound Control offers the option of a deep sport tone with a stirring growl on start-up.

300r engines

GO FARTHER, FASTER

The Racing 300R is designed to make full power on readily available 87-octane fuel. To squeeze more power from less fuel Advanced Range Optimization (ARO), a closed loop fuel-control system, utilizes electronic sensors to precisely adjust the fuel mixture for the best-possible efficiency at all speeds. Mercury Racing 300R is engineered to be reliable and durable. A rugged midsection is designed to handle all the high-performance abuse the water can dish out. Superior protection against corrosion begins with the industry’s lowest-copper aluminum alloy and exclusive, comprehensive finish treatments. These high-performance outboards are tested, tested and tested again – in the lab and on the water – in a never-ending quest to exceed the highest expectations.

view full specifications

FACTS & FIGURES

Full Throttle RPM

5800
6400

RATED HP

300

CYLINDERS

V8

DISPLACEMENT

4.6 L

Product Details

SHAFT LENGTH 20, 25, or 30
TRIM SYSTEM Standard or Heavy Duty
MID SECTION Standard, Heavy Duty or Racing AMS
SKEG Camber or Straight
WARRANTY 3-Year²
BORE & STROKE 3.6 x 3.4 IN/92 x 86 MM
INDUCTION SYSTEM Custom Racing Short-Runner Intake Manifold
FUEL REQUIREMENT Unleaded Regular 87 Octane Minimum (R+M/2) Or 91 RON 10% Ethanol Maximum
FUEL SYSTEM Electronic Fuel Injection (EFI) Computer Controlled With Advanced Range Optimization
IGNITION SYSTEM Digital Inductive
CHARGING 115 (AMS) / 85 (CMS)
IDLE CHARGE Yes
STARTING Electric Start With SmartStart Protection
OIL REQUIREMENT NMMA Certified FCW SAE 10W-30
JPO OPTION N (CMS), Optional (AMS)
THROTTLE & SHIFT CONTROLS DTS (AMS), DTS or Mechanical (CMS)
GEARCASE Torque Master, Sport Master or 5.44 HD
GEAR RATIO 1.85 (AMS), 1.75:1 (CMS) or 1.60:1 (CMS, AMS)
DRY WEIGHT 512 LBS
CARB STAR RATING 3
MINIMUM CENTERLINE MOUNTING DISTANCE (IN) 26
STEERING Electro-Hydraulic Power Steering
TIE BAR OPTION Integrated (AMS), Bracket (CMS)
IDLE RPM 600
MOUNTS Hard Rubber or Solid
ENGINE TYPE V-8 NA 4S
LUBRICATION SYSTEM Integrated Wet Sump
GEAR SHIFT F-N-R
ENGINE MANAGEMENT SYSTEM SmartCraft PCM 112
ENGINE PROTECTION SYSTEM SmartCraft Engine Guardian
EXHAUST SYSTEM Selectable
OIL CAPACITY 6.6L
STEERING ANGLE '+ / - 30°

PHANTOM BLACK

PHANTOM BLACK 300r

COLD-FUSION WHITE

COLD-FUSION WHITE 300r

Digital Throttle & SHIFT (DTS)

The precision of Digital Throttle and Shift (DTS) with available Mercury Racing Digital Zero Effort controls eliminates cable maintenance and delivers smooth shifting with instant throttle response.

300r throttle shift
300r Speed control

ADAPTIVE SPEED CONTROL

Adaptive Speed Control maintains engine RPM as load changes due to sea conditions or turning maneuvers to maintain boat authority with less control input.

SMARTCRAFT TECHNOLOGIES

The 500R model supports the full suite of Mercury SmartCraft technologies, including the Engine Guardian monitor system. Stream engine and performance data to a Mercury VesselView multi-function display or to many other multi-function displays.

300r Technology

Top Cowl SERvice door

Pop open the industry-exclusive Top Cowl Service Door for easy access to the oil dipstick and fill without removing the cowl.

1/
1/
1/
1/
color background

Ready for the Wide Open?

Authorized Mercury Racing dealers are marine performance experts ready to help you make your Wide Open dreams come true.

Find a Dealer