SPECIAL FOCUS: HANDHELD EQUIPMENT - Different Strokes

In the old days, handheld equipment was much simpler. Contractors
didn’t think much about their engine-style options because there really weren’t any. The two-cycle engine was standard on handheld equipment, and landscape professionals became accustomed to mixing oil with gas.

But in recent years, federal emissions standards have forced manufacturers to seek other options, including catalytic converters on two-stroke engines, four-stroke engines and combinations of two-stroke and four-stroke technology, as well as stratified-charged engines.

Two-stroke manufacturers face the challenge of meeting emissions requirements without drastically increasing costs and weight and decreasing power. At the same time, manufacturers of other engine technologies are trying to convince contractors that their equipment is the future because emissions standards will make two-cycle engines harder to find.

TWO-CYCLE TRADITION. Even some four-cycle engine manufacturers say two cycles are still the engines of choice among landscape contractors, mainly because of their lighter weight.

"We talked with landscape contractors in focus groups, and the No. 1 issue for them, without a doubt, is they do not want to add more weight to their products because it reduces their productivity," says Rob Stegall, director of emissions compliance and development, Echo, Lake Zurich, Ill.

Four-cycle engines can be a ½ to 1 pound heavier than two-stroke engines, according to engine manufacturers. A 25-cc two-cycle engine is approximately 1.1 pounds lighter than an equivalent-sized four cycle, says Bob Jensen, territory sales manager for Robin America, Wood Dale, Ill. "Landscape contractors themselves would prefer two-cycles because of the weight and simplicity," Jensen says.

Roscoe Klausing, president of Lexington, Ky.-based Klausing Group, tried a four-cycle trimmer but said it was too heavy and not powerful enough. "I am looking for a four stroke, but so far all the ones we tested have not worked as well as the two cycles," he says.

Two-cycle engines are lighter because they have 30 to 40 fewer moving parts than the standard and hybrid four-cycle engine, Stegall says, adding that 20 of those parts are moving. "That’s 20 more times probability that something can break, and moving parts rubbing together create friction, which causes more chance for overheating and product failure," he explains.

Tom Dibble, supervisor of technical services for Kawasaki, Grand Rapids, Mich., agrees that because two-stroke engines have fewer moving parts and no valves, they have less maintenance concerns. "With a four stroke, you need opening and closing valves and associated hardware," Dibble explains.

Two cycles also don’t require oil maintenance because the intake uses mixed fuel instead of an oil sump like four-cycle and hybrid engines, Stegall notes. Some four-cycle operators have complained that the engine stalls when turned on its side or upside down because it needs proper oil distribution, Stegall says.

Klausing says he’s noticed some of these problems with the four-cycle trimmer he tried two years ago. "You get in tall grass, and it bogs down faster than something else would," he says. "We’ve also noticed that the compression doesn’t seem to be as good when you are flipping it upside down or sideways, and the power decreases by 80 percent."

In addition to weight and performance concerns, four-cycle engines add at least $40 to $50 to the retail price of a handheld product, says Echo Vice President of Marketing Joe Fahey. Jensen estimates a higher number, saying that four-cycle engines add about $100 to a product’s retail cost.

"If I have to add 35 additional parts to a machine, that’s going to increase its costs," Stegall adds.

As such, two-cycle engine costs will increase in retail price by $10 to $20 in the near future with the addition of catalysts to comply with future emissions regulations, Fahey says. By 2005, engineers must reduce emissions from this year’s 74 grams per brake horsepower hour (g/bhp-hr) to 37 g/bhp-hr. Two-cycle manufacturers say catalysts will keep their products EPA compliant without significantly increasing costs. "Yes, it has an effect on cost because of the catalyst and some manufacturing technologies, but it’s probably the smallest impact in cost compared to some other technologies," Stegall explains.

Other than the catalyst, currently two-cycle engines require no additional parts, Stegall notes. "We’re not talking about weight increases, and we’re not talking about increased reliability concerns," he says. Also, increasingly stringent emissions standards have not affected engine power, according to Stegall. By experimenting with different piston shapes and catalyst designs, two-cycle manufacturers have maintained or even increased power.

"In the very beginning we, like everybody else, suffered some performance loss," Stegall explains. "We have actually regained all that power and have more power per cc now than we had before the regulations."

Decreased emissions have also improved fuel efficiency by 20 to 30 percent since regulations first went into effect, according to Fahey, because less fuel escapes through the muffler.

FOUR-CYCLE TREND. Landscape contractors may prefer the lower weight and price of two-cycle engines, but as regulations tighten, more manufacturers have been moving toward four-cycle technology because they’re able to meet emissions standards without significantly impacting performance.

"Rather than invest in two cycles, we felt everything was eventually going to have to be four cycle because it was the most economical and environmentally sound thing to do," Jensen says. "If you look at EPA and California regulations, they’re getting stricter, and it will get to the point where no two-cycle engine will be available. I’m sure that’s what’s going to happen."

Two-cycle manufacturers are struggling with how to design a catalyst that will reduce emissions without becoming too hot. They’re accomplishing this by adding sheet metal and guarding, making the product heavier and lessening its weight advantage over four cycles, explains Mike Braun, director of product development for the micro-engine unit at Briggs & Stratton, Milwaukee, Wis.

Power comparisons are also similar, according to Braun. For instance, one 34-cc four-cycle engine currently being marketed has the same or more horsepower as most 34-cc two-stroke models, Braun says.

In addition, two cycles typically spread their maximum torque over a smaller rpm range then four-cycle engines while four cycles’ torque spans a broader range of lower speeds, resulting in less wear and tear on the engine’s moving parts, Braun says. It also translates into improved sound characteristics.

Four cycles can also be 25 percent more fuel efficient than two-cycle engines because no fuel is used to push the exhaust gases out of the cylinder, Jensen says. Fuel may be four cycles’ No. 1 selling point. Contractors top complaint about two-cycle engines is the gas/oil mixture requirement.

"One of the things that surprised us is the number of people who disliked mixing fuel," says Ann Roche, vice president and general manager of Briggs & Stratton micro- engine business unit. Eliminating gas and oil mixtures may reduce some maintenance issues related to equipment users mixing the wrong grade of oil, Braun notes.

TWO-FOUR PUNCH. Some manufacturers are combining two- and four-cycle technology to comply with emissions standards. Like a typical four stroke, a hybrid features an overhead intake and exhaust valve and performs four piston strokes for each power stroke. But instead of an oil reservoir, the hybrid uses a gas/oil mixture.

No oil sump means less maintenance than typical four strokes while easily achieving the same cleaner fuel emissions identified with pure four-cycle engines, says Jay Larsen, product marketing and communications manager, Shindaiwa, Tualatin, Ore. It also reduces or eliminates the tendency that four strokes have for stalling during multi-positioned use, according to Larsen.

Some hybrids also contain a "supercharging" chamber that helps the engine to develop more horsepower and torque compared to traditional four strokes, Larsen says.

These engines are about a half-pound heavier than two strokes and can cost approximately $380 for a trimmer equipped with a 24-cc engine, Larsen explains, adding that hybrids run about $20 more at retail than two-cycle engines.

Another technology recently introduced is the stratified-charged engine. This engine reduces scavenging losses by introducing fresh air into the engine between exhaust gases and a fresh air/fuel mix.

These engines can reduce emissions by about one-third of conventional two-cycle engines, according to Tommy Tanaka, marketing manager, RedMax/Komatsu Zenoah America, Norcross, Ga. These engines require slightly more parts than a two-stroke engine but less than a traditional four stroke or hybrid.

Stratified-charged engines also use a gas/oil mixture and some have larger mufflers to reduce noise levels. These engines are similar in price and power to two-stroke engines, Tanaka says.

More contractors are showing interest in stratified-charged engines because they don’t require a catalytic converter, which can overheat the engine, and they don’t require as much maintenance as the hybrid and standard four-stroke engines, Tanaka explains.

REGULATORY IMPACT. Despite more alternatives to two-cycle engines, some manufacturers say two-stroke engines are still the best option and are here to stay.

"The emissions levels, as of Jan. 1, 2005 are going to stabilize with two strokes, and we feel confident that two strokes are not going away," Fahey explains. But two-cycle engines may continue to face challenges ahead if emissions standards increase again.

"Some of the old favorites that have been used for years may not be available in the future because they just can’t meet the emissions requirements, so many contractors are going to end up searching for replacement products," Fahey says.

Two-cycle manufacturers can currently meet federal requirements by adding catalysts, but Larsen says if emissions standards get tighter, two-cycle manufacturers will have to search for more solutions. One way two-cycle manufacturers can combat increasing costs is by earning credits from the EPA for meeting standards on other equipment they manufacture, which can then be applied toward non-compliant engines, Dibble says.

"Certainly, two stroke is not dead, but two stroke as we know it today is changing dramatically and, someday, may die off completely," Larsen says. "The simple straightforward two-stroke engines from yesterday are gone. Replacing them are leaner-burning two strokes, which register much higher exhaust gas temperatures and are less forgiving to engine failure."

Environmentally conscious contractors, such as Klausing, may also impact the demand for more four-cycle products. "I want to see manufacturers move toward things that aren’t polluting," he says. "But I know it’s going to take a while because two cycles have been perfected for 20 years."