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Engines - Emission rules shaping outboard technology

As emissions standards get tighter, boaters will continue to see more new 4-strokes and cleaner 2-strokes, though the traditional carbureted 2-stroke outboard hasn’t yet become extinct.

As emissions standards get tighter, boaters will continue to see more new 4-strokes and cleaner 2-strokes, though the traditional carbureted 2-stroke outboard hasn’t yet become extinct.

This is the final year of phase-in for the Environmental Protection Agency’s Tier 1 standard to reduce overall hydrocarbon and nitrogen oxide exhaust emissions by 75 percent. Implemented in 1998, the EPA 2006 standard imposes the strictest-ever emissions regulations for outboard engines in the United States, and contributed to advances in 4-stroke and cleaner direct-injection 2-stroke technologies. And these outboards should be in compliance for years to come, says John McKnight, director of environmental and safety compliance with National Marine Manufacturers Association in Washington.

Outboard emissions standards are based on the average emissions across a manufacturer’s family of engines. Manufacturers earn credits for engines certified below the Tier 1 standard, which can be used to sell engines certified above the standard, according to the EPA. That’s how manufacturers are able to continue selling old technology carbureted 2-strokes.

In most cases these 2-strokes are lighter and cheaper than new technology outboards, and engine weight should be taken into consideration when repowering. Yamaha carbureted 2-strokes that are still available range from 8 hp to 150 hp, and Bombardier Recreational Products continues to offer carbureted 2-strokes under the Johnson name while it rolls out new models of Evinrude E-TEC clean 2-strokes.

McKnight says the EPA will propose later this year to adopt the more stringent California Air Resources Board 2008 exhaust emissions standard, or three-star rating. The marine industry anticipates implementation in 2010 or 2011, he says.

CARB has its own three-tier rule that required outboards to meet EPA Tier 1 by 2001, make an additional 30-percent reduction by 2004, and to take 50 percent off that figure by 2008, McKnight says.

“The existing base technology of currently available 4-strokes and direct-injection 2-strokes will meet the three-star standard, with modification,” says McKnight.

Modification entails calibration changes, rather than new technology, he says. Whereas outboard manufacturers had to change the engine technology they were using to meet the EPA Tier 1 standard — hence the nine-year plan — there will be no phase-in period for the EPA Tier 2 standard, says McKnight.

Here’s some of the latest news from the major outboard manufacturers.

Suzuki has become the first manufacturer to announce a 300-hp V-6 4-stroke outboard. The DF300 has variable valve timing, a 55-degree engine block angle, digital sequential electronic fuel injection, and a dual overhead cam powerhead. Other notable features include a newly designed lower unit and new electronic throttle/shift control. The engine will be available in 25-inch and 30-inch shaft lengths. Pricing and further technical specifications were unavailable.

Suzuki Marine, based in Brea, Calif., also has introduced 2.5- and 25-hp outboards. The 2-cylinder V-Twin DF25 ($3,748), at about 152 pounds, weighs 50 pounds less than its 3-cylinder predecessor, according to Suzuki, and has a displacement of 32.8 cubic inches. The single-cylinder DF2.5 ($875) has 4.15-cubic-inch displacement and weighs 30 pounds.

BRP filled out its Evinrude E-TEC line with 60-degree V-4 and V-6 engines from 115 hp to 200 hp. E-TEC outboards are now available from 40 hp to 250 hp.

The 115-hp V-4 has a displacement of 105 cubic inches, and is based on the same block as the previous-ly introduced 130-hpE-TEC. The saltwater version of the 115 has a suggested retail price of $10,791 with a 20-inch shaft or $10,939 with a 25-inch shaft.

The 158-cubic-inchV-6s also are available with 20- or 25-inch shafts and carry suggested retail prices (20-inch) of $15,035 for the 150, $16,598 for the 175, and $18,041 for the 200. The company also has introduced the I-Command plug-and-play digital instrumentation system for E-TEC outboards.

Sturtevant, Wis.-based BRP now offers optional seven-year engine protection, or a $4 per horsepower rebate or credit on new E-TEC and other direct injection outboards from 40 hp to 250 hp. The standard limited warranty is three years.

Tohatsu Outboards and Nissan Marine have introduced a 115-hp TLDI (2-stroke low-pressure direct injection) engine. The 115 TLDI is the manufacturer’s largest engine, although it expects to develop a 135 TLDI within the next year, according to company sources.

Tohatsu also has introduced 2- and 3.5-hp 4-strokes. The company converts its carbureted 2-strokes to the TLDI system, which complies with EPA 2006 emissions regulations, using the same engine blocks and components as the carbureted models. The 4-cylinder 115 TLDI is available in 20- and 25-inch shaft lengths, has a 107.9-cubic-inch engine block, and weighs 380 pounds.

The Tohatsu 115 TLDI has a suggested retail price of $10,233, while its Nissan counterpart sells for $10,550. Tohatsu America/Nissan Marine is based in Carrollton, Texas. ,

Following the introduction of its Verado inline 4- and 6-cylinder supercharged 4-strokes from 135 hp to 275 hp, Fond du Lac, Wis.-based Mercury Marine has unveiled 75-, 90- and 115-hp 4-strokes. The three outboards are based on the 4-cylinder Verado engine block but shed such features as the supercharger, SmartCraft ignition, and SmartCraft digital throttle and shift.

The 75, 90 and 115 weigh 399 pounds, or about 110 pounds less than the 4-cylinder supercharged Verados. The new models keep the 16-valve dual overhead camshaft engine configuration, and include a tuned port integrated fuel and air management induction system, SmartCraft ECM 07 engine management, SmartCraft Engine Guardian system, and power trim and tilt. The 105.7-cubic inch outboards also use computer-controlled sequential multiport electronic fuel injection. Pricing was unavailable.

Yamaha Motor Corp. USA of Kennesaw, Ga. — whose lineup of 2- and 4-strokes ranges from 2.5- to 300-hp — has focused on accessories rather than new outboards over the last couple of years, including its Command Link digital information system, a throttle-and-shift control box for triple-engine installations, and the Multi-Function Tiller Handle. Since removing the model-year designation for its engines last year, Yamaha says it is under less pressure to introduce new models.

The company plans to manufacture 4-strokes larger than its F250 but says that will depend on market demand and whether or not there are boats capable of handling such a large outboard, according to company sources.

Honda Marine Group, based in Alpharetta, Ga., has been refining its line of 4-strokes from 2 hp to 225 hp. The company has reintroduced its 115-hp model as the BF115 Power Thrust. Power Thrust technology allows new gearcase and propeller designs for deck- and pontoon-boat applications, according to Brian Johnston, manager of Honda Marine public relations. Suggested retail prices are $11,154 (20-inch shaft) and $11,306 (25-inch).

The BF225, the most powerful outboard in Honda’s stable, has undergone gearing changes. A slightly smaller cam lobe has been added for improved trolling and low-rpm handling, according to Johnston. Combined with Lean Burn Feedback, which adjusts the fuel/air mixture according to speed and load, the gearing change equates to a nearly 20-percent improvement in fuel economy for the V6, he says. Suggested retail price is $18,216 (20-inch shaft).

In other news, Honda has introduced a five-year limited factory warranty on its BF40 through BF225 models. In addition, the company unveiled an iPAQ-based personal digital assistant called the Honda Diagnostic System. The hand-held HDS detects problems and related maintenance issues with the BF135, BF150, BF200 and BF225 models.