Suzuki's Award Winning Technology:

	"The Ultimate" DF250
	The Ultimate in Performance
	Compact Designs
	Durability and Reliability
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	DF 250 Specifications & Features

DOHC 24-Valve with VVT Delivers High Performance
Suzuki engineers designed a 3.6-liter V6 engine and an aggressive cam profile designed specifically for the DF250 to create the industry's first 250hp four -stroke outboard. However, their goal was not just to create an outboard that could deliver 250hp, but to create an outboard that could deliver high performance that suits its 250hp output along with the many benefits that a four-stoke can deliver.

A high performance camshaft designed to deliver 250hp produced the wanted power output, but to get the strong mid and low-end torque outboards need when accelerating requires altering valve timing. In general, only using camshaft setting like those found in racing engines produces an engine that develops insufficient low and mid range torque. This is because the valve timing for intake and exhaust differs according to load and engine speed.

The common idea is that the intake valve opens after the exhaust valve is fully closed however, the intake valve actually starts opening before the exhaust valve fully closes, creating a momentary overlap in the timing where both valves are open. Using VVT (Variable Valve Timing) in the DF250, this overlap can be increased or decreased by altering intake timing with the camshaft, thereby optimizing camshaft timing for low range and mid range operation. As the DF250's camshaft is already setup to deliver maximum output at high rpm, a change in timing in this range is mostly unnecessary. Increasing the overlap is necessary during acceleration in the low and mid power range, but no change in timing is required for stable idling. In the DF250's VVT system there are two chambers within the VVT actuator, one on the phase angle forward side and another on the phase angle backward side, to which hydraulic pressure is continuously applied to change the valve timing of the intake cam. When the engine is stopped, idling or other times that there is no oil pressure in the system, the VVT actuator locks, disengaging the system.

Multi-Stage Induction
Multi-stage induction enhances engine performance by changing the length of intake manifold pipes according to engine speed. The system utilizes two intake manifold pipes per cylinder, one operating at low engine speed and another operating at high. When the engine is operating at lower rpm, air enters the combustion chamber through the longer, curved manifold pipe. The length of the pipe is designed for entering the most suitable volume of fresh air into the chamber to improve combustion and boost low end torque.

As rpm's pass a preset threshold, the valve on the direct intake pipe opens up letting air enter directly into the combustion chamber, short, straight and lacking resistance it gets a greater volume of air into the chamber, increasing the engine's ability to breath at high rpm's, thus improving high speed power output.

The engine cover is designed with a large ail intake, which extends from the back of the cover, well around both sides to provide maximum airflow into the cowling.

Two-Stage Gear Reduction
With such a high performance engine now at your disposal, losing any power in the propulsion system would be a waste, so Suzuki engineers chose an efficient means of supplying maximum propulsion. A propeller rotating at high speed in the water has a tendency to slip and when two propellers of the same pitch but different diameters are rotated, the smaller propeller will slip more than the larger. So to obtain maximum propulsion, spinning a larger diameter propeller with a suitable pitch is the answer.

But to spin a larger propeller, more torque in the propeller shaft becomes necessary. In order to obtain the requires amount of torque however, the corresponding increases in weight and resistance due to the use of larger gears and a larger gearbox do not always provide effective results. The answer to this dilemma is found in the use of a two-stage reduction system that provides the necessary torque without adding unwanted bulk and weight.

The DF250 utilizes a first stage gear reduction (32:40) between the crankshaft and drive shaft, and a second stage reduction (12:22) in the lower unit's gear case, resulting in an overall gear ration of 2.29. This is the largest gear reduction ratio found in any outboard over 200hp two-strokes included. Such a powerful reduction allows the DF250 to turn a 16-inch diameter propeller, which, while being larger than the 14 1/2 inch diameter propeller found on the two stroke DT225, is also larger than those previously used on a V6 outboard. The propeller used on the DF250 is specially designed for greater acceleration and maximum speed.

Along with greater acceleration, the gear reduction in combination with the four stroke engine's wide power band is capable of handling a wide variety of loads, which is a significant benefit to boaters whose loads vary from day to day.

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