The original Innovation Award winning, DF300 broke new ground. It was the very first 300HP 4-stroke outboard and it set a new benchmark for performance and power from a compact and lightweight outboard.
Now Suzuki has taken this ultimate outboard to the next level. The addition of Suzuki’s Lean Burn Control technology and a new O2 (Oxygen) Sensor Feedback Control System provides boaters with a dramatic improvement in fuel economy as well as environmentally responsible operation, further enhancing the overall performance and value of the DF300, Suzuki’s flagship outboard motor.
Combining Suzuki’s advanced Lean Burn Control System, which is already utilized on the new generation DF90A/70A, DF60A, and the new DF50A/40A, with the Suzuki Precision Control system delivers even greater levels of fuel-efficient operation.
The new DF300 is the first Suzuki outboard to incorporate an O2 (Oxygen) Sensor Feedback Control System, which delivers cleaner and more stable emissions compared to prior systems and provides the engine with an optimum amount of fuel regardless of engine speed.
Suzuki’s flagship outboard also features technological advancements such as digital sequential electronic fuel injection, dual overhead cams with four valves per cylinder, variable valve timing, a long track intake manifold, and more. The DF300 is ideal for single, twin, or triple installations on a wide variety of boats.
Suzuki Precision Control (Electronic Throttle and Shift Systems)
Suzuki Precision Control offers boaters the latest in technologically advanced control systems. The core of the system is a sophisticated computer-based control system that does away with the mechanical cables found in conventional control systems, replacing them with electronic wiring that eliminates the source of friction and resistance. While you enjoy smooth, friction free throttle operation, the system’s computer is processing and transmitting commands in real-time to actuators at the engine that do all of the physical work, delivering precise throttle control with smoother, decisive shifting. This is most evident in the low rpm range where operation is noticeably smooth and accurate. 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 triple installation as well as dual station operation.
Suzuki’s Advanced Technologies Deliver the Utmost in Performance VVT (Variable Valve Timing)
Suzuki engineers designed a 4.0-liter V6 engine—the largest displacement found in the industry thus far—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), the DF300 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.
Long Track Intake Manifold
Another performance enhancing feature on the DF300 is a long track intake manifold. Using long intake pipes with an inline layout tuned to smooth airflow into the engine the system provides the DF300 with enhanced power.
Large Air Intake with Water Separator
The DF300 is 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 powerband 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.
Streamlined Gear Case
The gear case on the DF300 has a hydrodynamic design that reduces drag created as the lower unit moves through the water. This contributes to faster acceleration and increased speed.
Spherical Bore Throttle Body
A spherical bore throttle body smoothes the characteristically turbulently airflow into the engine that occurs as the throttle begins to open. Providing a smoother airflow during acceleration results in improved throttle control and stable engine operation at low rpm.
The cooler the fuel the denser it is, and the denser it is the better performance it delivers. Incorporating a fuel cooler in the DF300’s fuel delivery system cools the fuel before it enters the engine. Providing the engine with an optimum fuel supply results in better combustion and performance.
Suzuki outboards are among the most compact outboards in their respective classes. That’s due in part to the utilization of Suzuki’s proven offset driveshaft system. This design places the crankshaft in front of the driveshaft through the use of intermediate reduction gearing. In addition to providing an improvement in power performance and adding to the compactness of the outboard, this system moves the outboard’s center of gravity forward, resulting in contribution to weight distribution, balance, directional stability, and less vibration.
Two-Stage Cam Drive System
The DF300 utilizes a two-stage cam drive system that incorporates both gears and a chain. First stage gears transfer power between the crankshaft and the drive shaft from which a second stage utilizes 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’s Anti Corrosion Finish
The outside of the DF300 is covered with Suzuki’s anti-corrosion finish that is specially formulated to increase the durability of the engine and help protect parts of the aluminum exterior that are constantly exposed to saltwater. This advanced finish offers maximum bonding of the finish to the outboard’s aluminum surface, creating an effective treatment against corrosion.
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 improves resistance to wear and reduces friction.
New Suzuki Water Detecting System
Water in the fuel can be the source of poor combustion, lower power output, and corrosion. To protect the engine from moisture in the fuel, the DF300 is the first Suzuki outboard to utilize a water detecting fuel filter that alerts the operator with both visual and audio warnings when water is present in the fuel.
Water-Cooled Voltage Regulator
The outboard’s electric system includes a water-cooled voltage regulator that dissipates heat in the regulator to enhance engine durability.
Dual Engine Flush Ports
The build up of sand and salt in the engine’s cooling system can lead to engine damage. To aid in reducing such buildup, the DF300 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.
Fuses protecting the DF300’s electric system are assembled into a single fuse box located on the side of the outboard motor, which provides convenient access while offering a clean exterior.
32-Bit ECM and Suzuki’s Multi Point Sequential Electronic Fuel Injection
Suzuki pioneered the use of multi point sequential electronic fuel injection in four-stroke outboards with the introduction of the DF60 and DF70—the first four-stroke outboards designed with multi point sequential electronic fuel injection. At the heart of the DF300’s multi point sequential fuel injection system is the ECM (Engine Control Module), which constantly monitors crucial data, in real time, from a series of sensors placed in critical areas on the engine. This comprehensive network of sensors includes the Manifold Absolute Pressure Sensor, Crankshaft Position Sensor, Intake Air Temperature Sensor, Cylinder Wall Temperature Sensor, Camshaft Position Sensor, and Exhaust Jacket Temperature Sensor. Using a very powerful 32-bit computer, the ECM processes data from all of these sensors and instantly calculates the optimum amount of fuel to be injected at high pressure into each of the V6’s cylinders by the multi point sequential fuel injection system. Benefits of this system include reduced exhaust emissions, which allow the DF300 to comply with CARB 3-Star emission requirements, lower fuel consumption, smoother starts, crisper acceleration, smoother performance, and maximum efficiency.
Regulator with Dual Circuit Charging System
The DF300 incorporates a dual circuit charging system that can be adapted to accommodate the dual-battery configurations often used on large boats. When used in this configuration the system is designed to charge both the main and auxiliary batteries simultaneously but on independent circuits. With this you can drain down the accessory battery powering your electronics and still have a fully charged main battery for starting the motor.
Direct Ignition System
Supplying spark to the big V6 engine is an advanced ignition system that utilizes integral type spark plug caps with built-in ignition coils. The system is controlled by the outboard’s powerful 32-bit computer and provides each cylinder with optimum spark timing. In addition to reducing the number of parts and simplifying the wiring system, this arrangement greatly reduces electronic engine “noise” that can interfere with VHF radios, fish finders, and other marine electronics.
Suzuki Lean Burn Control System with 02 Sensor
The lean burn control system is designed to run on a thinner fuel mixture through the use of a lean air-fuel ratio. Suzuki engineers designed a system that predicts fuel needs according to operating conditions. It achieves added fuel economy through a reduction of pumping loss. In order to balance fuel efficiency with clean emissions, the system sets up air-fuel ratio taking advantage of the reaction characteristics of exhaust emissions. The system also has a wide lean burn range that extends up into the top speed range providing more efficient operation at cruising speed as well.
The addition of the 02 Sensor further improves the performance of the Lean Burn Control System, providing the computer with additional data to more efficiently control fuel burn under changing conditions, varying speeds and power demands. Initial internal testing indicates that the new DF300 with Lean Burn Control technology and the 02 Sensor is up to 14% more economical to operate than present models.
In addition to improved fuel economy, the 02 Sensor allows the DF300 to better control emissions and run cleaner than before.
Mechanically Efficient Design
Looking beyond fuel systems for solutions, Suzuki engineers explored ways they could improve efficiency by reducing mechanical loss. They designed a new oil pump that delivers greater mechanical efficiency and improved hydrodynamics in the lubrication system, allowing oil to move through the system with less resistance. In reducing mechanical loss in these and other areas, Suzuki has created a more efficient engine that contributes to better fuel economy.
High Output Alternator
The DF300 generates electricity from a high output alternator that delivers 54A (12V) of electrical power. Suzuki’s design allows the alternator to produce a majority of its output at low rpm, so even when operating at 1000rpm it can produce approximately 38A of power. In most situations, this is enough power to keep an assortment of electronics up and running.