Suzuki DF325A Specifications
| Engine Model: Suzuki DF325A |
| Engine Type: 4-stroke 6-cylinder DOHC 24-valve gasoline outboard engine |
| Total Displacement: 267.9 cu.in (4.4 L) |
| Rated Engine Power: 325 Hp (239 kW) at 6000 rpm |
| Fuel System: Multi point sequential electronic fuel injection |
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The Suzuki DF325A is a technological
masterpiece that perfectly balances awesome power with practical
efficiency. Built around a potent 4.4-liter V6 powerhead with a high
10.5:1 compression ratio, it delivers robust torque for powering heavy
loads without requiring premium fuel.
The revolutionary contra-rotating dual propeller system provides
superior underwater grip, distributing engine torque evenly over six
blades to enable a smaller, more hydrodynamic gearcase design while
delivering exceptional stability and acceleration.
Advanced features including the Dual Injector System for precise fuel
atomization, the Dual Louver System for moisture-free air intake, and
Suzuki's Lean Burn Control System for optimized fuel efficiency combine
to create an outboard that delivers awesome power with maximum
efficiency for the most demanding applications.
Engine Model: Suzuki DF325A
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 and Variable Valve Timing
Bore and Stroke: 98.0 mm x 97.0 mm (3.86 in x 3.82 in)
Piston Displacement: 4390 cc (267.9 cu. in)
Maximum Output: 239.0 kW (325 Hp)
Full Throttle Operating Range: 5300-6300 rpm
Fuel Delivery System: Multi-Point Sequential Electronic Fuel Injection
with Dual Injectors, Lean Burn, and Oxygen Sensor Feedback
Alternator: 12V 54A
Trim Method: Power Trim and Tilt
Gear Ratio: 2.29:1 with 2-Stage Gear Reduction
Gear Shift: F-N-R (Forward-Neutral-Reverse) via Suzuki Precision Control
Drive-by-Wire
Control System: Suzuki Precision Control (Digital Drive-by-Wire)
Exhaust: Through Prop Hub Exhaust
Propeller Selection: 12"-31.5" pitch, Contra-Rotating Dual Propellers
(Front and Rear, both 3-blade type, 15" diameter)
Starting System: Electric with Suzuki Easy Start System
Ignition System: Full-transistor Solid State Direct Ignition
Engine Lubrication: Trochoid pump pressure lubrication
Engine Oil Capacity: 8.0 L (8.5/7.0 US/Imp. qt.)
Gear Oil Capacity: 3.2 L (3.4/2.8 US/Imp. qt.)
Fuel Type: Alcohol-free unleaded gasoline
Minimum Fuel Octane Rating: 91 (Research method)
Spark Plugs: NGK ILZKR7D8
Spark Plug Gap: Standard: 0.7-0.8 mm (0.028-0.031 in)
CARB Emissions Rating: 3-Star Ultra-Low
The DF325A is built around a potent 4.4-liter V6 powerhead with a narrow
55-degree bank angle, making it the largest displacement V6 outboard in
its class and providing the tremendous torque essential for pushing
heavy loads efficiently. The block features a high-performance
compression ratio of 10.5:1, delivering impressive power output and fuel
economy without requiring high-octane fuel.
To withstand the higher forces generated by this compression ratio, the
pistons undergo shot peening treatment, which creates fine dimples on
the surface to evenly distribute combustion pressure, while the
connecting rods and associated hardware are engineered for exceptional
durability. The upper portion of each piston features an alumite coating
for increased heat resistance, while a resin coating on the piston skirt
reduces friction and wear for smooth operation.
The powerhead incorporates a DOHC 24-valve configuration for optimal
airflow and combustion efficiency. A self-adjusting oil-bathed timing
chain with automatic hydraulic tensioner drives the camshafts, providing
maintenance-free operation for the engine's lifetime. Variable Valve
Timing (VVT) controls the opening and closing timing of the intake
valves depending on engine operation.
By coupling an aggressive cam profile designed for maximum output at
high rpm with VVT, the engine delivers the additional torque needed for
accelerating in the low to mid-range, creating momentary overlap where
both intake and exhaust valves are open for optimum timing across all
operating ranges.
The offset driveshaft design positions the crankshaft in front of the
driveshaft, moving the outboard's center of gravity forward. This
configuration makes the outboard more compact, improves weight
distribution on the boat's transom, reduces vibration, and enhances
steering stability.
The DF325A's fuel system represents a significant advancement with its
Dual Injector System, which uses two smaller injectors per cylinder to
provide immense precision, improved atomization, and increased fuel
efficiency. Injecting fuel achieves two critical functions: atomizing
the fuel for combustion and cooling the cylinder. The dual injector
design ensures complete fuel injection at precisely the right time and
angle for optimal power and cooling, increasing output by 3 percent
without causing knocking.
The Suzuki Lean Burn Control System supplies the appropriate air-fuel
mixture depending on navigation conditions, using an O2 sensor feedback
loop to optimize efficiency across all speed ranges, particularly at
cruising speeds. This combination with the Suzuki Precision Control
electronic throttle system offers improved fuel economy across a wide
operating range.
The Knock Sensor monitors combustion to provide optimized performance
while maximizing power output and increasing engine durability. A large
81mm throttle body ensures adequate air supply for the high-output
powerhead.
The DF325A employs a trochoid pump pressure lubrication system to ensure
consistent pressurized oil delivery to all critical engine components,
including the crankshaft, connecting rods, and valve train with VVT
components. The engine has an oil capacity of 8.0 liters. An oil filter
is conveniently located for easy maintenance access.
Cooling efficiency is enhanced by a dual water inlet system, a critical
feature for high-performance operation. The engine's cooling system
relies on water supplied through two water inlets located on the lower
unit where conventional outboards have only one. This configuration
increases water flow, providing better cooling performance especially at
high speeds.
The DF325A features water inlets on the tip of the gearcase, taking
advantage of the dynamic pressure caused by the movement of the gearcase
through the water to maintain stable water suction even at very high
speeds. The secondary inlet positioned lower allows the engine to
operate effectively in shallow water conditions. For post-operation
maintenance, the Fresh Water Flushing System allows easy connection of a
garden hose to rinse salt, sand, and other debris from the cooling
passages, protecting the engine from corrosion.
| Mid Section and Lower Unit |
The mid-section and lower unit of the DF325A house its most
revolutionary features. The Suzuki Dual Prop System spins two propellers
rotating in opposite directions on a single engine, providing more grip
underwater and distributing engine torque evenly over six blades instead
of three. This configuration reduces torque per propeller, allowing gear
diameter to be reduced and enabling a smaller, more hydrodynamic
gearcase design that moves through the water with less resistance.
The 2-Stage Gear Reduction system incorporates the offset driveshaft
with a first stage reduction between the crankshaft and drive shaft, and
a second stage reduction inside the gear case. This design makes the
2.29:1 gear ratio possible, allowing the engine to turn large diameter
propellers with tremendous power for quick acceleration and high
propulsive efficiency even under heavy loads.
The advanced gearcase design utilizes computational fluid dynamics to
minimize resistance while providing highly efficient water flow to the
propellers. The contra-rotating propeller configuration produces
exceptional stability when driving straight by eliminating the lateral
forces associated with single propeller designs, while also generating
powerful reverse thrust for greater maneuverability. The gear material
has been changed with special heat treatment to endure the added thrust
and inertial mass from the powerful reverse thrust generated by the
contra-rotating propellers.
The Power Trim and Tilt system provides hydraulic control over the
outboard's angle, allowing the operator to adjust boat trim for optimal
performance, fuel efficiency, and ride comfort. The Tilt Limit System
prevents the outboard from tilting beyond a selected angle, protecting
both the engine and boat from damage due to excessive tilting.
The DF325A is designed specifically for the Suzuki Dual Prop System
featuring contra-rotating propellers with a three-blade front and
three-blade rear configuration. The recommended propeller pitch
selection ranges from 12 inches to 31.5 inches, with both front and rear
propellers having a diameter of 15 inches. Available propeller pitches
include 15.5, 18, 19.5, 21, 22.5, 24.5, 27, and 31.5 inches.
The propeller blade geometry has been optimized to work in this
configuration, resulting in incredible grip and acceleration across the
rev range, with the configuration recording high speeds even under heavy
loads and at high rotation speeds. The Watergrip Propeller, featuring 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)
Transom Height (Extra-Extra Long Shaft - XX): 762 mm (30 in)
Dry Weight (Extra Long Shaft - X): 330 kg (727 lbs)
Dry Weight (Extra-Extra Long Shaft - XX): 339 kg (747 lbs)
Engine Mounting: Shear mount rubber damper 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
Gear Oil Capacity: 3.2 L (3.4 US qt.)
Spark Plugs: NGK ILZKR7D8
Spark Plug Gap: Standard: 0.7-0.8 mm (0.028-0.031 in)
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)
Large Sports Fishing Boats: Ideal for offshore center consoles and
sportfishing boats requiring powerful thrust for quick planing and
exceptional handling in offshore conditions, as demonstrated by the 10m
Naiad Kirby achieving 0-40km/h in just 3.5 seconds with twin DF325A
installations. Cruising Catamarans and Large Cruisers: Provides the
muscle needed for express cruisers, cabin cruisers, and catamarans, with
the 12.5m Naiad YWE achieving a cruise range of 391 NM or 725 km at
optimal cruise speed with twin installations.
Commercial Applications: Built for everyday use in commercial operations
where reliability, durability, and fuel efficiency are paramount for
pushing heavy loads, with the ability to run on widely available 91 RON
fuel making it ideal for global applications. Premium Chase Boats:
Selected as the official outboard for INEOS Britannia, the Challenger of
Record for the 37th America's Cup, with twin DF325A outboards powering
the team's chase boats, demonstrating the engine's performance,
reliability, and ability to keep pace with race boats during critical
testing and training.
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