Suzuki DF250AP Specifications
| Engine Model: Suzuki DF250AP |
| Engine Type: 4-stroke 6-cylinder DOHC 24-valve gasoline outboard engine |
| Total Displacement: 250 cu.in (4 L) |
| Rated Engine Power: 250 Hp (184 kW) at 6000 rpm |
| Fuel System: Multi point sequential electronic fuel injection |
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The Suzuki DF250AP is a technologically
sophisticated outboard that delivers premium power and precise control.
Based on the flagship DF300AP platform, it incorporates Suzuki's
Selective Rotation, allowing a single model to serve as either a
standard or counter-rotating engine for superior twin installation
performance. The engine features a 55-degree V6 block with Dual Overhead
Cams (DOHC) and 24 valves, ensuring robust power delivery.
Suzuki's Lean Burn Control System works in concert with the electronic
Precision Control throttle and shift to optimize fuel efficiency across
a wide operating range, from low-speed trolling to cruising. A
redesigned low-drag lower unit, dual water inlets for enhanced cooling,
and a suite of advanced features like Variable Valve Timing (VVT) and a
water-detecting fuel system make the DF250AP a durable, efficient, and
high-performing choice for serious boaters.
Engine Model: Suzuki DF250AP
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 two-stage
cam drive system
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: 184 kW (250 Hp)
Full Throttle Operating Range: 5500-6100 rpm
Fuel Delivery System: Multi-Point Sequential Electronic Fuel Injection
Alternator: 12V 54A
Trim Method: Power Trim and Tilt
Gear Ratio: 2.08:1
Gear Shift: F-N-R (Forward-Neutral-Reverse) via Suzuki Precision Control
(Drive-by-Wire)
Control System: Suzuki Precision Control (Electronic)
Exhaust: Through Prop Hub Exhaust
Propeller Selection: 15" - 27.5" pitch
Starting System: Electric
Ignition System: Fully-transistorized
Engine Lubrication: Trochoid pump pressure lubrication
Engine Oil Capacity: 8.0 L (8.4 US qt)
Gearcase Oil Capacity: 1.1 L (1.2 US qt)
Fuel Type: Automotive gasoline (94 research octane recommended)
Spark Plugs: NGK BKR6E
CARB Emissions Rating: 3-Star Ultra-Low
The DF250AP is built around a potent 4.0-liter V6 powerhead with a
narrow 55-degree bank angle, which contributes to its remarkably compact
size. The block is designed for high performance and durability,
utilizing strengthened forged pistons. The upper portion of these
pistons features an alumite coating for increased heat resistance, while
a resin coating on the piston skirt reduces friction and wear.
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 years of
maintenance-free operation.
Suzuki's Variable Valve Timing (VVT), hydraulically controlled by oil
pressure, optimizes intake valve timing to maximize torque in the low
and mid-range, delivering the robust acceleration an outboard needs. The
offset driveshaft design also positions the powerhead forward, shifting
the center of gravity for a more compact mounting footprint and improved
weight distribution.
The DF250AP's fuel system is highly advanced, centered on the Suzuki
Lean Burn Control System. This technology uses an O2 sensor feedback
loop to predict fuel needs based on operating conditions, allowing the
engine to run on a more efficient, leaner air-fuel mixture during a wide
range of speeds, from low-speed operation into the cruising range.
This results in significant fuel economy improvements, with in-house
testing showing the DF300AP to be 14% more economical than its non-Lean
Burn predecessor without sacrificing power. This system works seamlessly
with the Multi-Point Sequential Electronic Fuel Injection, which
precisely meters fuel to each cylinder for optimal combustion.
Additional fuel system components include a fuel cooler to increase fuel
density for better combustion and a large air intake with a water
separator to keep moisture out of the electronic throttle body. A 81mm
spherical bore throttle body smooths turbulent airflow during
acceleration for enhanced throttle control.
The DF250AP employs a trochoid pump pressure lubrication system to
ensure a consistent and reliable supply of pressurized oil 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. Regular oil changes, as outlined
in the maintenance schedule, are essential for long-term durability.
Cooling efficiency is enhanced by a dual water inlet system, a
significant feature of the DF250AP. 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,
especially at high speeds and during operation in shallow water
conditions. A water pump, located in the lower unit, circulates water
through the engine.
For post-operation maintenance, the DF250AP is equipped with dual
freshwater flush ports - one on the rear panel and one on the front -
making it exceptionally convenient to flush salt, sand, and other debris
from the cooling system whether the boat is in or out of the water.
| Mid Section and Lower Unit |
The mid-section and lower unit of the DF250AP are where some of its most
groundbreaking features reside. It utilizes a newly designed, low-drag
gearcase that, while larger internally to accommodate more durable
components, has a smoother, more hydrodynamic external shape that slices
through the water with less resistance and greater efficiency. The
hallmark feature is Suzuki Selective Rotation.
This world-first system integrates both regular and counter-rotation
operation into a single lower unit. By changing the gear-shift mode and
using a counter-rotation propeller, the same outboard can operate in
either direction.
This is made possible by a special, unified design of gears, shafts, and
bearings, with redesigned gears using a different alloy and larger
diameters for superior rigidity and durability. The lower unit also
features an aggressive 2.08:1 final drive ratio, allowing it to turn a
large 406mm (16-inch) diameter propeller for powerful thrust and
excellent performance on a wide variety of boats. Exhaust is channeled
through the propeller hub for quieter operation.
The Power Trim and Tilt (PTT) 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 a tilt limit feature to prevent the outboard from being raised
beyond a safe point for operation, protecting both the engine and the
boat from damage.
The owner's manual provides guidance on adjusting trim angle to maintain
proper steering stability and avoid conditions like "porpoising" or
"plowing". A wide trim and tilt range is available for various running
conditions and for tilting the motor for trailering or beaching.
The DF250AP is designed to work with a range of high-performance
stainless steel propellers to match various boat types and load
conditions. The recommended propeller pitch selection ranges from 15
inches to 27.5 inches.
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. Selecting the
correct propeller is essential to allow the engine to operate within its
designated full-throttle range of 5500-6100 rpm.
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): 274 kg (603 lbs)
Dry Weight (Extra-Extra Long Shaft - XX): 279 kg (614 lbs)
Engine Mounting: Shear Mount system
Initial Service: Perform at 20 hours or 1 month.
Engine Oil and Filter: Replace every 200 hours or 12 months.
Gearcase Oil: Replace every 200 hours or 12 months.
Spark Plugs: Inspect every 100 hours or 12 months; replace every 300
hours or 36 months.
Use NGK BKR6E. Spark Plugs Torque: 25-29 Nm (18-21 lb-ft).
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).
Low Pressure Fuel Filter: Inspect every 200 hours or 12 months.
Water Pump Impeller: Inspect per schedule; replacement interval varies.
External Anodes: Inspect every 200 hours or 12 months.
The Suzuki DF250AP is a versatile, high-performance outboard suited for
a broad spectrum of demanding applications, from recreational to
commercial use. 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.
High-Performance Cruisers: Provides the muscle needed for powering
express cruisers and other large trailerable boats. Pontoon and Deck
Boats: Its potent V6 power is well-suited for large, heavy pontoons and
deck boats that require substantial torque for planing and pulling water
sports.
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