Suzuki DF300APX Specifications
| Engine Model: Suzuki DF300APX |
| Engine Type: 4-stroke 6-cylinder DOHC 24-valve gasoline outboard engine |
| Total Displacement: 250 cu.in (4 L) |
| Rated Engine Power: 300 Hp (220.7 kW) at 6000 rpm |
| Fuel System: Multi point sequential electronic fuel injection |
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The Suzuki DF300APX is a technologically
supreme outboard that redefines expectations for V6 marine power. Built
around a 4.0-liter powerhead with a narrow 55-degree V-angle, it
delivers its rated 300 Hp with remarkable smoothness and refinement. The
engine incorporates Suzuki's Lean Burn Control System, which optimizes
fuel efficiency across the operating range, providing significant
improvements in fuel economy from low-speed operation through cruising
speeds.
The world-first Selective Rotation system integrates both regular and
counter-rotation operation into a single lower unit, a revolutionary
advancement for twin and triple-engine installations. With Suzuki
Precision Control electronic throttle and shift, Variable Valve Timing,
and a host of durability enhancements, the DF300APX delivers the
ultimate combination of power, efficiency, and sophisticated control.
Engine Model: Suzuki DF300APX
Engine Type: 4-Stroke, 55° V6, DOHC (Double Overhead Camshaft), 24-Valve
Number of Cylinders: 6
Valve Train Drive: Self-adjusting oil-bathed timing chain with automatic
hydraulic tensioner
Bore and Stroke: 98.0 mm x 89.0 mm (3.86 in x 3.50 in)
Piston Displacement: 4028 cc (250 cu. in)
Maximum Output: 220.7 kW (300 Hp)
Full Throttle Operating Range: 5700-6300 rpm
Fuel Delivery System: Multi-Point Sequential Electronic Fuel Injection
with Lean Burn and Oxygen Sensor Feedback
Alternator: 12V 54A
Trim Method: Power Trim and Tilt
Gear Ratio: 2.08:1 (Two-stage Reduction Gear)
Gear Shift: F-N-R (Forward-Neutral-Reverse) via Suzuki Precision Control
Control System: Suzuki Precision Control (Drive-by-Wire)
Exhaust: Through Prop Hub Exhaust
Propeller Selection: Standard Rotation: 17", 18.5", 20", 21.5" pitch
(three-blade stainless steel)
Starting System: Electric with Suzuki Start System
Ignition System: Fully-transistorized Solid State Direct Ignition
Engine Lubrication: Trochoid pump pressure lubrication
Engine Oil Capacity: 8.0 L (8.5 US qt.)
Gearcase Oil Capacity: 1.1 L (1.2 US qt.)
Fuel Type: Automotive unleaded gasoline (89-94 research octane
recommended)
Spark Plugs: NGK BKR6E
CARB Emissions Rating: 3-Star Ultra-Low
The DF300APX is built around a potent 4.0-liter V6 powerhead with a
narrow 55-degree bank angle, contributing to its remarkably compact
dimensions. The block is engineered for high performance and durability,
utilizing strengthened components throughout. The powerhead incorporates
a DOHC 24-valve configuration for optimal airflow and combustion
efficiency.
A key innovation is the two-stage cam drive system, which first uses
gears to transfer power from the crankshaft to a driveshaft, and then a
self-adjusting, oil-bathed timing chain with an automatic hydraulic
tensioner to drive the camshafts. This design allows for a more compact
cylinder head and provides maintenance-free operation for the life of
the engine.
Suzuki's Variable Valve Timing system, hydraulically controlled by oil
pressure, optimizes intake valve timing to maximize torque in the low
and mid-range. The system automatically adjusts valve timing by altering
intake camshaft timing, creating momentary overlap where both intake and
exhaust valves are open, resulting in optimum timing for low and
mid-range operation. This delivers the robust acceleration essential for
outboard applications.
Engineers designed the V6 4.0-liter motor with an aggressive cam profile
that delivers maximum power and performance at high rpm. Coupling this
cam profile with the VVT system provides the additional torque needed to
accelerate in the low to mid-range.
The DF300APX's fuel system is highly advanced, centered on the Suzuki
Lean Burn Control System. This innovative technology uses an O2 sensor
feedback loop to predict fuel needs according to operating conditions,
allowing the engine to run on a more efficient, leaner air-fuel mixture
from low-speed operation through the cruising range. This system
delivers its benefits over a wide operating range, providing significant
improvements in fuel economy.
The combination of the Lean Burn system with the electronic throttle and
Suzuki Precision Control shift system allows precise control over engine
RPM to improve fuel economy in a broader operating range. This
combination also offers smooth power transitions throughout the entire
RPM range.
The engine is equipped with an O2 Sensor Feedback Control System that
enables cleaner and more stable emissions by controlling the air-fuel
ratio across each of the engine's operating ranges, providing an optimal
amount of fuel to the engine regardless of RPM.
Additional fuel system enhancements include a fuel cooler that cools
fuel before it enters the engine. Cooler fuel becomes denser, and denser
fuel offers better combustion and more performance. An 81mm spherical
bore throttle body smoothes the turbulent airflow into the engine that
occurs as the throttle begins to open, providing increased throttle
control and stable engine operation at low rpm.
A long tube intake manifold provides smooth airflow into the engine,
delivering enhanced low-range power. The large air intake duct maximizes
airflow into the motor for maximum power output, producing more low to
mid-range torque and providing a broad power band. The system also
features a water separator to help keep moisture out of the electronic
throttle body and a heat shield to prevent the engine from heating the
intake air.
The DF300APX employs a trochoid pump pressure lubrication system to
ensure consistent and reliable pressurized oil delivery to all critical
engine components, including the crankshaft, connecting rods, and the
valve train with its VVT components. The engine has a substantial oil
capacity of 8.0 liters.
Cooling efficiency is enhanced by a dual water inlet system, a
significant feature of the DF300APX. By positioning one water intake at
the gearcase nose and a second lower intake, the system increases water
flow into the cooling passages, delivering greater cooling efficiency.
The forward inlet at the gearcase nose delivers a greater water supply,
especially at high speeds, while the second inlet positioned lower
allows the engine to operate effectively in shallow water conditions.
For post-operation maintenance, the DF300APX is equipped with freshwater
flushing ports, making it convenient to flush salt, sand, and other
debris from the cooling system.
| Mid Section and Lower Unit |
The mid-section and lower unit of the DF300APX house its most
groundbreaking features. The newly designed low-drag gearcase was
developed specifically to accommodate the Suzuki Selective Rotation
system. While the case itself is larger than the previous model to
provide increased gear durability, it is designed with a smoother, more
hydrodynamic shape that allows it to move through the water with less
drag and greater efficiency.
The hallmark feature is Suzuki Selective Rotation, a world-first system
that integrates both regular and counter-rotation operation into a
single lower unit. The system consists of a new arrangement of
transmission gears in the lower unit that allows the outboard to
function in regular or counter-rotation mode, and a switch connected to
a circuit in the engine compartment that activates counter-rotation
mode. In counter-rotation mode, power is transmitted through the reverse
gear, which has been engineered with the same characteristics as the
forward gears.
With the addition of Suzuki Selective Rotation, gears in the lower unit
were redesigned using a different alloy and slightly larger diameters
delivering greater rigidity, and are specially heat treated creating
gears that are highly durable.
The lower unit utilizes an aggressive final drive ratio of 2.08:1,
incorporating two-stage gear reduction. This large reduction gear ratio
leads to powerful torque for quick acceleration and great top-end speed,
allowing it to turn a large 406mm (16-inch) diameter propeller available
in various pitch sizes for optimum performance on a wide variety of
boats. Exhaust is channeled through the propeller hub for quieter
operation.
The Power Trim and Tilt system provides hydraulic control over the
outboard's angle, enabling the operator to adjust the boat's trim for
optimal performance, fuel efficiency, and ride comfort. The system
includes tilt limit features to protect both the engine and boat from
damage.
The DF300APX is designed to work with a range of high-performance
stainless steel propellers to match various boat types and load
conditions. Recommended propeller pitch selections for standard rotation
models include 17 inches, 18.5 inches, 20 inches, and 21.5 inches, all
three-blade stainless steel designs.
The robust 2.08:1 gear ratio and the low-drag gearcase are engineered to
effectively transfer the engine's power to a large 16-inch diameter
propeller, optimizing thrust and overall performance. The Watergrip
Propeller, a stainless steel propeller with a new interchangeable
square-shaped bush, offers efficient conversion of engine power to
propulsion resulting in better grip and performance.
Transom Height (Extra Long Shaft - X): 635 mm (25 in)
Dry Weight (Extra Long Shaft - X): 290 kg (639 lbs) w/battery cable, w/o
transmission and motor oil
Engine Mounting: Rubber damper mounting system
Engine Oil Capacity: 8.0 L (8.5 US qt.) with filter
Recommended Oil: High-quality 4-stroke outboard oil, NMMA FC-W certified
Gearcase Oil Capacity: 1.1 L (1.2 US qt.)
Spark Plugs: NGK BKR6E
Spark Plug Gap: 0.7-0.8 mm (0.028-0.031 in)
Spark Plugs: 25-29 Nm (18-21 lb-ft)
Valve Clearance (Intake): 0.23-0.27 mm (0.009-0.011 in) (cold)
Valve Clearance (Exhaust): 0.33-0.37 mm (0.013-0.015 in) (cold)
Offshore Sports Fishing Boats: Its power, durability, and advanced
features like Selective Rotation for twin installations make it ideal
for offshore center consoles and sportfishing boats in the 24 to 30-foot
range. The 2026 C-Hawk 25 Center Console is factory-rigged with the
Suzuki DF300APXW5, demonstrating its suitability for saltwater fishing
applications.
Luxury Pontoon Boats: The 2026 Starcraft RX 23 Q DH luxury pontoon is
powered by a Suzuki DF300APX 300 HP Four-Stroke, showcasing the engine's
capability in delivering exceptional acceleration, smooth handling, and
quiet confidence for premium pontoon applications. High-Performance
Cruisers: Provides the muscle needed for powering express cruisers,
cabin cruisers, and other large trailerable boats.
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