Suzuki Raises the Bar
By Brian J. Boltz
Venerable manufacturer Jumps to the Head of the Class
Ocean Reef, FLA - With much fanfare, and an impressive multi-media display held in the theater at the famed Ocean Reef Club in Key Largo, Florida, Suzuki Marine formally launched the latest three big engines in their new V6 4-stroke lineup. In front of more than 50 journalists and writers from around the world, and another 50 or so worldwide distributors, Rick Suzuki himself told the gathering that these new motors: the DF 200, DF 225, and DF 250 represent the greatest step forward in the history of the company. With the introduction of these engines, the company served formal notice to the industry that it not only intends to be a player, but it plans on achieving a leadership position in 4-stroke technology. In many respects, it already has.
In reaching this milestone for the 2004 model year, Suzuki completes the transition begun back in 1998–to convert its entire line of engines to 4-stroke, from the portable 4 HP to the new flagship 250 HP. The latter is put forth as the first 250 HP 4-stroke engine in the industry, and the largest displacement 4-stroke motor available anywhere. At 3.6 liters (220.5 cubic inches), we know of none bigger. The company now boasts a range of 16 engines, all 4-stroke technology.
Having already won two IMTEK industry awards for their design, Suzuki would not rest on their laurels. The new DF 250 won yet another NMMA Innovation Award, presented at the recent Miami International Boat Show. Considering the laundry list of new features and technological advances, it is not hard to see why the judges saw fit to honor the company one more time.
Suzuki engineers started with a clean sheet of paper when they set out to develop the latest three powerhouses that were formally introduced this week (or more likely a virgin CAD/CAM file on their workstation). To begin with, in order to achieve a more compact, slimmer profile, they changed the V-6 block angle to 55 degrees–something no other manufacturer has done. This goes a long way toward eliminating the "giant eggbeater look," and along with an offset driveshaft creates a remarkably well-balanced engine in appearance, and on the transom.
Variable Valve Timing
Another exclusive feature of the DF 250 is variable valve timing. While seen in other applications such as Formula 1 auto racing motors, this is a first in the marine industry. Suzuki engineers considered it critical to achieve the low-end to mid-range torque needed for larger boats and their heavier loads. Under normal operating conditions, there is a momentary overlap when both intake and exhaust valves are open. A hydraulic phase adjuster on the camshaft controls precise increases or decreases of this overlap by advancing or retarding intake timing in relation to the crankshaft. Opening the intake valve earlier in the low-end and mid-range allows for more efficient intake, a stronger power stroke, reduced emissions, and improved fuel economy.
Another exclusive feature used on the DF 225 and the DF 250 is an air intake system, which adjusts to the demands on the engine based on different rpm. These engines feature two intake pipes per cylinder–one for low engine speeds and one for high engine speeds. At low rpm, air enters the combustion chamber through the longer, curved pipes. The curves allow the most suitable volume of air in the chamber to improve combustion and boost low-end torque. When rpm passes a pre-set threshold, a valve is actuated that allows air to enter the chamber directly through a short, straight pipe, boosting efficiency and high speed power output–sort of like what tuned headers do for exhaust air on the way out.
Multi-Point Electronic Fuel Injection
Suzuki's advanced digital sequential fuel injection is controlled by an Electronic Control Module (ECM), a 32-bit computer that monitors engine data in real time and instantly calculates the optimum amount of fuel to be injected under high pressure into each cylinder. High-performance plate-type injectors provide superior fuel atomization and cleaner combustion.
The ECM also drives new, advanced, built-in diagnostics, which allow service technicians to plug in and rapidly download operating history data, assisting them in pinpointing any problems.
Another innovative feature is Suzuki's direct ignition system, which builds the ignition coil right into the spark plug cap. This reduces the parts count, simplifies wiring, and helps eliminate electro magnetic interference, (EMI), which can mess with other electronics on the boat.
Integrated, High-Output Alternator
Because the alternator is integrated with the flywheel, the high-power, 54-Amp alternator requires no separate, power-robbing belt drive. This configuration provides cooling airflow from the flywheel fins, and is designed to crank 32 Amps of power at only 1,000 rpm. This means your electronics, lights, and pumps keep working–even at trolling speeds.
Two-Stage Gear Reduction
Suzuki faced another challenge as they designed these new motors: how to get the power from the engine to the prop, literally. Losing any power in the propulsion system would be a waste. 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 prop will slip more than the larger. So to obtain maximum propulsion, spinning a larger diameter prop with a suitable pitch is the answer. But to spin a larger prop, more torque in the shaft becomes necessary. In order to obtain the required amount of torque however, the corresponding increases in weight and resistance due to the use of larger gears and larger gearbox do not always provide effective results. The answer: a two-stage gear reduction system that provides the necessary torque, without adding unwanted bulk and weight.
The DF 250 uses a first stage gear reduction (32:40) between the crankshaft and driveshaft, and a second stage reduction (12:22) in the lower unit¹s gear case, resulting in an overall gear ratio 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 DF 250 to turn a 16-inch prop, which, while being larger than the 14-1/2" prop found on the two-stroke DT 225, is also larger than those previously used on a V6 outboard. The prop used on the DF 250 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.
Thoughtful Incidentals that Aren't Incidental
Some motors run so quiet at idle; you don't know they have been started. Or you simply forget when there are no obvious signs or signals. Everyone knows what it's like when you try to crank an already running engine. Suzuki eliminates that one from your horror story list with a starter system that prevents the starter from engaging if the motor is running. The operator must turn the key to "off" before the starter can be engaged. In addition, the starter will not operate if the safety stop key is not inserted–so you can't start if you can't stop.
A multi function tachometer is available, which takes data from multiple engine sensors, alerting the operator to any problems that may require attention. An additional function is an oil change reminder light, set off when–based upon normal operating conditions, it's time to change engine oil.
The motor tilt system incorporates a user settable tilt limit switch, which prevents the motor from tilting beyond a predetermined position. This protects both the boat and the motor from damage when a motor is tilted too far.
Performance, and Clean Too
Not to be forgotten, the DF250 has received the CARB three-star rating, which identifies engines that meet the California Air Resources Board's 2008 exhaust emission standards. The strictest exhaust regulations to date, they represent a 65% reduction in emissions from the EPA 2006 standards.
The New Frontier
It can be said that Suziki has thrown down the gauntlet, so to speak; that they aim to take share in the burgeoning 4-stroke market. In Europe, between 2001 and 2002, Suzuki's market share doubled in the 102HP to 149HP segment. In the US, share went from 6.9% in 2001, to 15.2% in 2002 in that same segment. It is clear that they are finding their audience, and successfully penetrating these markets with their new products. At the top end, the jury is still out when it comes to the competitive angler who makes up the sweet spot of the market. Here is where Suzuki seeks to unseat the dominant incumbents, and where the battle will be waged. It has happened before, and with world-class products, there is no reason to believe that it cannot happen again. The coming years will be very interesting, as the giants face off to win the hearts and minds and transoms of this lucrative market.