Two-way Water Inlet

The 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

A 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 Durability

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. The gears are specially heat treated creating gears that are highly durable.

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 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

Suzuki’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

The 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

Another 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

Specially 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

Water 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

An 81mm spherical bore throttle body smoothes 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

A 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

Water 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

The buildup of sand and salt in the engine’s cooling system can lead to engine damage. To aid in reducing such buildup, 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’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 analog gauges.