The race to green

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Common rail direct fuel injection helps make this Cummins diesel more efficient while enhancing its performance.

Common rail direct fuel injection helps make this Cummins diesel more efficient while enhancing its performance.

Although alternative energy sources such as electric, solar, propane and natural gas continue to inch their way into the marine market, the advances in diesel and gasoline engines in the past five years already have boosted the environmentally friendly factor on the water.

“Since we believe we are part of the problem, we have to be part of the solution — that’s what guides us,” says Volvo Penta of the Americas president Ron Huibers.

With recent advances in technology, such as common rail direct fuel injection, and a sharp drop in the prices of gasoline and diesel fuel, the internal combustion engine appears to be thriving in an age when alternative power sources are developing at a robust pace. Developers of electric propulsion systems for the marine market realize their products won’t be replacing the gasoline and diesel engines anytime soon.

“I have been a boater all my life and still enjoy getting my hands dirty working on a gas engine,” says Joe Fleming, chief engineer of the electric marine engine company Elco Yachts. “However, younger people are embracing electric [propulsion power]. It takes time for things to change. In 50 years people will likely still love their gas and diesel engines, but electric power will continue to make great strides.”

Elco sells 70- and 100-hp electric inboards and 5-, 7- and 9.9-hp outboards (with a 25 to debut this spring). The company will come out with a 150- to 200-hp inboard in the near future, says Fleming. The upstate New York company also has a new hybrid electric/diesel inboard propulsion system that uses a 20-hp Elco electric motor and a 425-hp Cummins diesel inboard. The system, installed in a Beneteau Swift Trawler 34, made an appearance at the Miami International Boat Show in February.

Volvo Penta's Gen V gasoline sterndrive engines now have common rail direct fuel injection, a technology already used on its diesels.

Volvo Penta's Gen V gasoline sterndrive engines now have common rail direct fuel injection, a technology already used on its diesels.

The Miami show also was a showcase for diesel and gasoline engines. Engine makers have been pushed to clean up their products. The Environmental Protection Agency’s Tier III emissions mandates went into effect from 2010 to 2012, prompting engine manufacturers to design and build cleaner diesel engines. Engine makers such as Cummins Marine build powerplants that manage the fuel in the combustion process with the implementation of common rail fuel injection.

“When I started with Cummins Marine 10-plus years ago, the first engine I worked on was mechanically governed fuel-injection timing,” says Carl Hertwig, a combustion performance and emissions engineer. “We had a boat at the dock with two engines. We would start it up in the morning, and there were giant white clouds of unburned fuel that would travel across the docks. It was just terrible, so one of my first goals was to eliminate this scenario.”

The switch from the mechanically to the electronically controlled engine was a huge step in the right direction. Cummins Marine’s QSM11 engines became the company’s first electronic engines in 1999-2000, followed by the QSB and QSC series from 2002 to 2004.

“We are far below the visible [smoke] levels and we are to the level where you can barely smell [exhaust] when you first start up,” says Hertwig.

Common rail fuel injection in an electronically controlled engine gave Cummins — and other manufacturers — a way to “pressurize and meter” the fuel. The engine’s brain — the electronic control module, or ECM — manages a slew of important actions during combustion. It measures engine position, boosts fuel pressure, predicts airflow and monitors coolant temperature. The electronically controlled injectors shoot fuel into the combustion chamber three major times (pilot injection, the main event and post-injection) to squeeze more power out of the fuel instead of releasing it as fumes and smoke.

“The ECM algorithms control the fuel system, based on engine speed, temperatures and pressures in the engine,” says Hertwig. “These responses are much more finely controlled over different engine conditions. I liken the ECM to our brain, the algorithms to how we have been programmed to respond to our senses, and the pressure control and injectors are outputs like our muscles.”

You're looking at the main fuel-injection event on the piston of a Cummins QSB6.7 diesel just before combustion.

You're looking at the main fuel-injection event on the piston of a Cummins QSB6.7 diesel just before combustion.

Cummins Marine has benefited from the improvements in instrumentation accuracy required for automotive emissions standards, measuring airflow to 0.5 percent accuracy, for example, says Hertwig. Twenty test cells run 24/7 at the Cummins test center in Charleston, S.C. Engine testing costs about $2,000 a day, says Hertwig.

Cummins Marine has benefited from its parent company’s truck and heavy machinery R&D.

“EPA tier III emissions standards for on-highway trucking went into effect several years before marine,” says Andy Kelly, Cummins Marine marketing communications manager.

Like Cummins, Volvo Penta leans on its commercial product and R&D. “The toughest emissions regulations in the world are for U.S. on-highway trucks — the EPA 2010 rule — and Volvo Penta responded,” says Huibers. “Since then we’ve built on that.”

When it comes to gasoline engines, Volvo Penta points to a number of improvements that have contributed to decreased pollution, such as switches from fixed cam to variable valve timing, cast iron to aluminum blocks and raw water to closed-looped cooling. But one particular advance stands out.

“If we narrow it down to one item, then it would be the move to electronic direct fuel injection,” says Mel Cahoon, Volvo Penta’s gas product manager for engineering. “We are up to directly injecting fuel into the cylinder at 2,050 psi now, which replaces port fuel injection, which was on the order of 40 to 50 psi.”

General Motors’ Gen V gasoline engines are now being built with common rail fuel injection. Volvo Penta’s new 200- and 240-hp sterndrive engines made their first public appearance at the Marine Dealer Conference & Expo last fall. The 200/240, which are 4.3-liter V6 catalyzed engines, are the first of a fleet of sterndrives that will use General Motors Gen V engines. Volvo Penta will roll out the complete new family of next-generation V6 and V8 gasoline sterndrives this year and in 2016.

Outboards continue to pack the same punch, but in lighter propulsion packages. Mercury and Yamaha second-generation 115 outboards are now at fighting weights well under 400 pounds (for their short-shaft models, the Yamaha F115 is 377 pounds and the Mercury is 363 pounds.)

Yamaha recently came out with freshwater versions of its V6 outboards that maximize top speed. The new MAX SHO outboards consist of 115-, 150-, 175- and 250-hp models. The 150 and 250 are long-shaft models.

Mercury, with its most recent introduction, has produced another powerplant with an excellent power-to-weight ratio. With its newest Verado engines, the company has re-engineered the 2.6-liter V6 300-hp used for the Verado 300 to create 350- and 400-hp Verados. The latter falls under the Mercury Racing umbrella, but can still be used to power non-racing, high-performance boats.

The new Verado generates 16 percent more peak power than the 300. Along with internal changes, managing engine frictional loss and temperature has allowed Mercury to achieve its horsepower-to-weight ratio, says Larry Teeling, category manager for Mercury outboards.

The Verado 350’s new cold-air intake system is designed to collect cool air from outside the cowling and deliver it to the supercharger. Engineers created a larger, straighter airflow path for less turbulent airflow. The water-cooled supercharger delivers greater boost by using water from the engine cooling system to provide a cooling jacket around the supercharger.

The durability factor

Although engine makers are working hard to squeeze every bit of performance from smaller engines, they are also focusing on maintaining durability.

“You start reaching the limits of the engines,” says Volvo Penta emissions regulations manager Rich Kolb. “We run at so high a power level and as lean as we can for efficiency. Walking the tightrope between low emissions and fuel economy and engine durability — that’s one of the most challenging jobs we face.”

For companies selling electric marine motors, the biggest hurdle is the excessive weight and the large size of batteries.

However, battery development is moving at a rapid pace. “There are companies who say by the end of 2015 they will be making batteries that have four times the energy density of lithium batteries and 12 times that of lead acid batteries,” says Fleming. “The energy density should increase by 20 to 30 percent by 2018. Nothing changes overnight, but this can change the direction technology is going.”

The rapid drop in fuel prices may slow the electric power movement, but it will go forward, says Fleming. “It looks like [fuel prices] are going to stay down for a while, but everything is cyclical and there’s no guarantee they won’t spike back up,” he says.

Major engine manufacturers are open to electric propulsion. In fact, Mercury a few years ago brought an express cruiser with hybrid propulsion to the Miami International Boat Show.

“We track battery technology and have done experiments and research with electric power and will continue to keep an eye on it,” says David Foulkes, Mercury’s vice president of product development, engineering and racing. “We are quite a long way from sustaining planing speeds for a long period of time with battery technology, at least with current technology.”

Volvo Penta’s research and development includes the testing of hybrid technology in marine applications, says Huibers. “We have yet to get to that crossover point where the marketplace will pay for the cost of the technology,” he says.

Advances in technology, engineering and materials have led to the production of diesel outboards in Europe. Cimco Marine Diesel AB of Sweden recently introduced a 200-hp diesel, the OXE Diesel, primarily for commercial and military boats.

“Combining the inboard reliability with the outboard flexibility and marrying them to a diesel propulsor has been the goal and Holy Grail of the marine industry for decades,” Pim Polesie, Cimco vice president, wrote in an email to Trade Only. “Cimco Marine Diesel AB has now developed a unit that effectively achieves this.”

Cimco is busy setting up dealer networks in Europe, with an eye on the U.S. market.

“The OXE Diesel is available for selected customers at the moment,” Polesie says. “They will be available for a broader market in October this year, but only on the markets where we have established distribution networks. The price is 35,000 euros to the end user. This is approximately $40,000.”.

The intercooled and electronically fuel-injected OXE weighs between 650 and 705 pounds, depending on shaft length. The Yamaha F200 4-stroke weighs 487 pounds. The Volvo Penta 200-hp 2.4-liter D3 inboard weighs 778 pounds with a dual-prop sterndrive.

The engines will be available in the U.S. when Cimco has established the right distributor network, says Polesie.

Alternative power for commercial boat applications is more easily justified because the engines can show their benefit over the course of extended use.

“Right now we have a 34-foot boat on Lake George (N.Y) that will do 100 miles on a charge — that is with lead acid,” says Fleming. “With lithium batteries we are talking 300 miles, and with the batteries of the near future you are talking about 1,000 miles on a charge. It’s getting interesting.”

Interesting, but not yet practical.

“Bringing new technology for the sake of new technology is not in the best interest of our customers,” says Huibers. “The diesel engine today is the most efficient — has the best thermal efficiency. And these gasoline engines are following suit.”

This article originally appeared in the March 2015 issue.


Maine Boatbuilders Show opens tomorrow

In its second year in a new location, the Maine Boatbuilders Show opens tomorrow at 10 a.m. at the Portland Sports Complex. Sail and powerboats, plus engines and accessories will all be on display.