Suzuki Selective Rotation
In multi-outboard installations on large boats, a counterrotation outboard is usually paired with a regular rotation model to help keep the boat traveling on an even keel and in a straight line. The DF300AP/250AP is built with special counter rotating gearing in the lower unit, which causes the prop to rotate in the opposite direction. Suzuki Selective Rotation eliminates the need to purchase a dedicated counter-rotation outboard by using a special switch that when connected to a circuit inside of the engine compartment, turns a regular rotation outboard into a counter-rotation model with a counter rotational propeller. This industry first is made possible through a special, unified design of gears, shaft, and bearings in the lower unit that are designed to operate reliably and efficiently in either regular or counter-rotation directions
New Lower Unit
Compared to the original DF300, the biggest changes you’ll find on these outboards are in the lower unit, which was redesigned for the Suzuki Selective Rotation system—the world’s first integration of regular and counter-rotation models into a single unit. The system consists of a new drive gear layout in the lower unit that allows the outboard to operate in either regular or counter-rotation mode, and a switch that connects to a circuit in the engine compartment that engages the counter-rotation mode. Like the DF300, the new DF300AP/250AP utilises an aggressive final drive ratio of 2.08:1 allowing it to turn a 406mm (16-inch) diameter propeller available in various pitch size for optimum performance on a wide variety of boats. Changes to gear designs provide greater durability, and adding a two-way water inlet changes water flow into the cooling system for increased cooling efficiency.
Two-way Water Inlet
Two-way Water InletThe engine’s cooling system relies on water supplied through low water intakes located on the lower unit. Utilising this dual low water inlet configuration increases water flow into the lower unit, which delivers greater cooling efficiency. Positioning the forward inlet at the gear case nose delivers a greater water supply especially at high speeds. The second inlet is also positioned lower allowing the outboard to operate in shallow water conditions
Newly Designed Low Drag Gear Case
Newly Designed Low Drag Gear CaseA redesigned low drag gear case developed to accommodate the new gears utilised in the Suzuki Selective Rotation system. The case itself is actually larger than the previous model to provide increased gear durability, however it is designed with a smoother, more hydrodynamic shape that allows it to move through the water with less drag and greater efficiency. Areas with the highest drag are indicated in red in the illustrations below. The comparison shows that the new design allows the lower unit to slice through the water with less drag.
Superior DurabilityWith the addition of Suzuki Selective Rotation, gears in the lower unit were redesigned using a different alloy and slightly larger diameters delivering greater rigidity. The gears are specially heat treated creating gears that are highly durable.
Suzuki Precision Control (Electronic Throttle and Shift)
Suzuki Precision Control (Electronic Throttle and Shift)Suzuki Precision Control is a technologically advanced computer-based control system that replaces the mechanical control cables found in conventional control systems with electronic wiring that eliminates the source of friction and resistance. While you enjoy smooth, little friction throttle and shift operation, the system’s computer is processing and transmitting commands in real-time to actuators at the engine that deliver precise throttle controls with smoother, decisive shifting. This is most evident in the low rpm range where operation is noticeably smooth and accurate.
When combined with Suzuki’s Lean Burn Control System it allows control of fuel and air flow to boost the limit of the controllable revolution range improving fuel economy over a wide operating range. Suzuki Precision Control also features built-in systems that help guard the engine and drive against damage due to mishandling, and its design and simple wiring make installation easy, reducing the time required for rigging and adjustment. The system offers precision control for single, twin or triple installation as well as dual station operation.
Suzuki’s Lean Burn Control System
Suzuki’s Lean Burn Control SystemSuzuki’s innovative Lean Burn Control System was first introduced on the DF90A/80A/70A to great acclaim from boaters and the media alike.
It predicts fuel needs according to operating conditions allowing the engine to run on a more efficient fuel mixture through the use of a lean air-fuel ratio. It delivers its benefits over a wide operating range, providing significant improvements in fuel economy from low-speed operation into the cruising range. Combining this system with the Suzuki Precision Control, electronic throttle and shift system, allows the operator precisely control to increase or decrease the engine RPM for improved fuel economy over a wider operation range. This combination also delivers smooth power transitions throughout the entire RPM range. In-house testing shows that while cruising, the DF300AP is 14% more economical than the original non-Lean Burn DF300 without sacrificing any power of the original DF300.
Advanced Technology Delivers the Utmost in Performance
Advanced Technology Delivers the Utmost in PerformanceSuzuki’s engineers designed the 4.0-liter V6 engine with an aggressive cam profile that delivers maximum output and performance at high rpm. In coupling this cam profile with Suzuki’s advanced Variable Valve Timing (VVT), delivers the additional torque that outboards need for accelerating in the low to mid-range. VVT achieves this by adjusting the timing of the intake valves, allowing them to open before the exhaust valves are fully closed, creating a momentary overlap in the timing where both sets of valves are open. Using VVT, this overlap can be increased or decreased by altering intake timing with the camshaft resulting in optimum timing for low and mid-range operation.
Strengthened Forged Pistons
Strengthened Forged PistonsThe upper portion of pistons used in the big V6 engine is treated with an alumite coating that increases heat resistance. A resin coating applied to the piston skirt increases resistance to wear and reduces friction.
Long Track Intake Manifold
Long Track Intake ManifoldAnother performance enhancing feature on the new engine is a tuned long track intake manifold. Using long intake pipes tuned to provide smooth airflow into the engine the system provides the DF300AP & DF250AP with enhanced low-end power.
Large Air Intake with Water Separator
Large Air Intake with Water SeparatorSpecially designed with a large air induction port to maximize airflow into the engine in order to obtain maximum power output. The increased airflow produces more low- to mid-range torque and provides a wide power band that is necessary in an outboard engine. Suzuki also designed the system with a water separator, which aids in keeping water out of the electronic throttle body and a heat shield to keep intake air from being heated by the engine.
Suzuki Water Detecting System
Suzuki Water Detecting SystemWater in the fuel can be the source of poor combustion, lower power output, and corrosion. To help protect the engine from moisture in the fuel, the DF300AP/250AP are the first Suzuki outboards to utilise a water detecting fuel filter that alerts the operator with both visual and audio warnings when water is present in the fuel.
Spherical Bore Throttle Body
Spherical Bore Throttle BodyAn 81mm spherical bore throttle body smoothens the turbulent airflow into the engine that occurs as the throttle begins to open. Providing a smoother airflow during acceleration results in increased throttle control and stable engine operation at low rpm.
Two-Stage Cam Drive System
Two-Stage Cam Drive SystemA two-stage cam drive system incorporates both gears and a chain. First stage gears transfer power between the crankshaft and the drive shaft from which a second stage utilises a chain to deliver power from the driveshaft to the camshaft. This system allows for the use of smaller cam sprockets, which in turn allow for a reduction in valve angles also reducing the size of the cylinder head. An automatic hydraulic tensioner incorporated into the timing chain system keeps the chain properly tensioned and provides years of maintenance-free operation.
Suzuki Water Detecting System
Suzuki Water Detecting SystemWater in the fuel can be the source of poor combustion, lower power output, and corrosion. To help protect the engine from moisture in the fuel, a water detecting fuel filter is fitted to alert the operator with both visual and audio warnings when water is present in the fuel.
Easier Maintenance Dual Engine Flush Ports
Easier Maintenance Dual Engine Flush PortsThe build up of sand and salt in the engine’s cooling system can lead to engine damage. To aid in reducing such build up, the DF300AP/250AP is designed with two freshwater flush ports that make flushing of the cooling system as convenient and easy as possible. With one port located on the rear panel and the second on the front panel, access is easy and flushing out the system is possible whether the boat is in or out of the water.
Suzuki Troll Mode System (Optional Equipment)
Suzuki Troll Mode System (Optional Equipment)Suzuki’s Troll Mode system provides finer control over engine speed at low rpms to keep your boat moving at a constant speed while trolling. When the system is engaged, revs are controlled with an independent control switch that adjusts engine revs in 50rpm increments over a range spanning from idle to 1,200rpm. The system includes a control switch, which can be mounted nearly anywhere on the console, and a tachometer, and is compatible with Suzuki’s SMIS digital gauges or the dual scale analogue gauges.
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|Recommended Transom Height (mm)||L: 508, X: 635, XX: 762|
|Weight (kg*)||L: 284, X: 290, XX: 299|
|Engine type||DOHC 24-Valve|
|Piston Displacement (cm³)||4,028|
|Maximum Output (kw)||183.9|
|Recommended Fuel||RON94 / AKI89|
|Gear Ratio||2.08 : 1|
|Exhaust||Through Prop Hub Exhaust|
|Fuel Delivery System||Electronic Fuel Injection|
|Bore X Stroke (mm)||98 x 89|
|Full Throttle Operating Range (rpm)||5,500 - 6,100|
|Oil Pan Capacity (L)||8.0|
|Fuel Tank Capacity (L)||-|
|Trim Method||Power Trim and Tilt|
|Propeller Selection (Pitch)||15" - 27.5" (R/R), 17" - 26" (C/R)|