They’ve got the power: What you need to know about mower engines

August 15, 2019 -  By
Crew member fueling up mower (Photo: Tony Ventouris)

FUEL UP More efficient fuel consumption is one of the biggest recent advancements in engine technology. (Photo: Tony Ventouris)

Mower engines have come a long way since the first internal combustion engine (ICE) was put into a commercial lawn mower by Ransomes of Ipswich in England in 1902.

“Internal combustion engines are changing as government regulations and market competition increases,” says Ken Logan, product strategy manager at Kawasaki. “Of course, the physics hasn’t changed for ICEs — intake, compression, spark, exhaust — but the technology of how to do this has. More power is coming out of engines while lowering fuel consumption, improving exhaust emissions and increasing engine life.”

Well over a century later, it is hard to even conceive of using a lawn mower that isn’t powered by an engine, especially if it is being used on a large commercial or residential property.

Recent developments and innovations in commercial mower engine technology can help landscape contractors save fuel and money. The power they afford can also help companies be more efficient, even if they have fewer employees, which is important in an industry experiencing a dwindling labor market.

Many of the latest innovations in engines have been introduced to enable mowers to cover more ground in less time, says Brett Wegner, product manager, Kohler Engines. “With tightened labor markets, productivity has become more critical because time is money,” he adds.

When it comes to a commercial mower engine, the fuel choice is perhaps one of the biggest deciding factors, and more efficient fuel consumption is one of the biggest recent advances in engine technology. Fuel and the rate at which it’s consumed can determine cost of ownership, environmental impact and engine performance.

“All different fuels have their place,” Wegner says. “The benefits depend on the type of equipment you’re using and the fuel source that’s most readily available and cost-effective for your specific use.”

No matter what type of fuel a landscape contractor chooses to use in his or her mowers, developments in engine technology ensure he or she will likely experience a cost savings, benefit from environmental friendliness and see an increase in power.

Saving green

“Certainly engine products today are far more efficient than they used to be,” says Kris Kiser, president and CEO of the Outdoor Power Equipment Institute. “One of the ways you get to emissions conformity is by reducing the amount of fuel you burn, so if you have an emissions requirement, you’ll burn less fuel. Engines have gotten far more efficient as of late.”

If an engine burns less fuel, it stands to reason that less money will be spent on fuel. Electronic fuel injection (EFI) is one innovation in engine technology that helps landscape contractors use fuel more efficiently, which in turn, saves them money.

Propane-powered engine (Photo: Kohler)

KEEP IT CLEAN Propane-powered mowers are cleaner burning than their gasoline or diesel counterparts. (Photo: Kohler)

EFI systems — which have been commonly used in automobiles for many years — work to precisely meter fuel in the engine to optimize performance and fuel efficiency. While some commercial mower engine manufacturers have been using EFI for several years, for many, it is still new technology.

According to John Deere’s engineering team, EFI reduces machine cost without sacrificing performance. EFI machines do not have carburetors, which often require routine maintenance or replacement — both of which can be costly and lead to downtime.

The sensor technology in an EFI engine optimizes performance by adapting to operating conditions.

“For example, in applications like an urban area where you’re doing a lot of transport time between parking lots and different areas where you’re not running the (power takeoff), it’s not consuming as much fuel because the engine doesn’t have to power all those areas,” explains Natalie Haller, product marketing manager for commercial mowing at John Deere.

The technology allows engines to continuously adjust engine performance in response to changes in operating conditions — such as external temperature and altitude.

Engines equipped with EFI technology are able to make adjustments as they run, so fuel is always being used in the most efficient manner, no matter the operating conditions and, most importantly, if the operating conditions change. Not only does this save companies money, but it also adds to the machine’s green factor.

Electric mowers (Photo: Mean Green Mowers)

IT’S ELECTRIC Electric or battery-powered mowers serve as options to completely eliminate emissions. (Photo: Mean Green Mowers)

The fuel system itself is constantly readjusting, measuring and tweaking its air-fuel ratio hundreds of thousands of times per minute and optimizes the performance of the engine to put out the least emissions and be as fuel-efficient as possible, says Jeremy Wishart, director of off-road business for the Propane Education & Research Council (PERC).

EFI technology is now common on gasoline-powered engines, but there are only a few manufacturers that have adopted it for propane engines, according to Wishart. He says he expects several companies to announce EFI propane engines in the fourth quarter of this year or the first quarter of next.

Other efficiencies incorporated into today’s mowers that can save contractors money include: cast-iron cylinder liners; aluminum block; large capacity air, fuel and oil filters; high-performance spark plugs; and hydraulic valve lifters, Wegner says.

Fuel choice is another way contractors can save money on their mowers. Though gasoline is still the most common fuel of choice for mower engines, according to Briggs & Stratton, switching to an alternative fuel like propane will cost more upfront but overall can help a company’s bottom line.

According to Wishart, unlike traditional fuels such as gasoline or diesel, propane is less susceptible to market volatility and less likely to see fluctuations in price due to weather, geopolitical conflict, a refinery going down or even regional price differences.

Because a landscape contractor can lock in fuel price with a propane retailer, he or she can more effectively budget for fuel, since generally, the price won’t change until the contract is renewed.

Going green

Environmental, or green, initiatives are top of mind for many engine manufacturers. As emissions regulations get ever stricter, companies must find ways to make their engines more environmentally friendly, which is another area where EFI comes in.

Diesel engine (Photo: John Deere)

POWER UP Gasoline and propane-powered mowers offer the same amount of power to the engine. Diesel engines, however, provide more torque. (Photo: John Deere)

“With older carbureted engines, you’re basically tuning it for one operating condition, and that’s usually max power. And max power equals max fuel consumption, unfortunately,” Wishart says.

Decreasing fuel consumption not only decreases the amount of money operators have to spend on fuel, but it also decreases the amount of engine emissions.

Other companies have committed to developing engines that run on cleaner-burning alternative fuels.
Propane engines have gained some traction in recent years due to their lower emissions and financial incentives from the government and PERC that can help make the purchase of new propane-powered equipment more affordable, Wegner says.

“Since propane is a cleaner-burning fuel, propane models are ideal for states that enforce Ozone Action Days, when mowing with carbureted gasoline engines is limited,” Wegner adds.

When EFI is added to an already clean-burning propane engine, the environmental impacts are lessened even further. And with more engine manufacturers jumping on board to develop propane EFI engines, they are becoming more readily available.

Other engine companies are embracing the green trend, not just by the type of fuel they use, but by what the engines themselves are made out of. Briggs & Stratton’s commercial mower engines are comprised of 98 percent recycled aluminum.

“Not 100 percent of the materials can be recycled, but many of the materials can be,” says Michelle Gross, senior director of marketing for North America in Briggs & Stratton’s global engines and power group.

Even diesel-powered engines, which have historically been some of the dirtier engines, are getting more environmentally friendly. “There have been significant strides in diesel, whether it’s injection or filtering because emissions requirements are tightening,” Kiser says. “Oftentimes the cost of fuel will dictate the product choice and selection. But certainly diesel manufacturers have made significant progress in making engines cleaner.”

According to Haller, the John Deere Z997R, which is a diesel engine, was in final Tier-4 compliance a full year ahead of the mandated regulation, just to support the cleaner emissions.

Tier-4 emissions standards are the strictest Environmental Protection Agency (EPA) requirements for off-road diesel engines. According to the EPA, to meet Tier-4 emission standards, engine manufacturers must produce new engines with advanced emission control technologies, and in-use diesel fuel must decrease sulfur levels by more than 99 percent, since the emission control devices can be damaged by sulfur.

Kohler manufactures diesel engines from 9.1 to 134 hp for a wide variety of equipment. These engines are unique because they meet Tier-4 standards without the use of a diesel particulate filter, Wegner says. The diesel particulate filter removes soot from the exhaust of a diesel engine.

Not only is this part of the engine often bulky and inefficient, Wegner notes, but the filter can also be costly to replace. Being able to eliminate it altogether saves money and the downtime associated with engine repairs.

“We have a lot of faith in our manufacturers that they will be able to meet any emissions requirements,” Kiser says.

Mowing green

Josh Willis of Greenscapes Land Care, Worton, Md.(Photo: Tony Ventouris,

Josh Willis of Greenscapes Land Care, Worton, Md.(Photo: Tony Ventouris,

Ultimately, no matter what kind of engine a mower comes equipped with, it is important to find the one that is right for a company’s intended application, budget and fuel availability. Overall, gasoline-powered engines are still the most popular, according to Gross. One of the benefits of a gasoline engine is the prevalence of the fuel.

“For most commercial lawn mower applications, gasoline is preferred because it delivers proven performance and is relatively inexpensive, easy to use and readily available,” Wegner says.

Gasoline is everywhere at every fuel station in every town, Haller notes. It is not always easy to find diesel, and securing propane typically requires a contract with a local propane retailer.

It’s also likely that if a gasoline engine needs maintenance, a landscape contractor is going to be able to find someone who can fix it. “Gas engines are easier to service because most of the small engine repair shops focus on gas engines,” Gross adds.

Performance-wise, propane and gasoline operate about the same, but there is a notable power difference when it comes to diesel engines, which do afford operators a bit more power under the hood, Haller says.

According to Haller, diesel provides more torque, so if an operator is mowing through thick or tall grass, diesel engines are going to give them more power and provide a better quality cut the first time around. Unfortunately, the power comes at a price. Diesel still has the stigma of being one of the dirtier fuels.

“Diesel has greater power density than gasoline, but it has a reputation to overcome … (Think of) that thick black billowing cloud of smoke belching out of the exhaust you see from trucks on the highway,” Logan says.

Propane, while clean burning, especially when compared to diesel, has a stigma of its own to shake off. According to Wishart, landscape contractors often believe propane won’t afford them the same type of power they’re used to working with.

Wishart explains that all of the rumors landscape contractors have heard about propane-powered mowers are generally just that, rumors. “Give it a try on one mower,” he says. “You’ll experience that the power is going to be the same, the maneuverability is going to be the same.”

According to Kiser, as long as the correct engine is paired with the right mower, a user is going to experience the intended amount of power paired with the best fuel economy.

“There are a wide variety of engines. The key is finding what product works best (for your application),” he says. “Manufacturers are terrific at this. The key there is to identify what engine is best and then make them available in the marketplace.”


It stands to reason that the simplest way to save money on fuel and reduce emissions is to eliminate the internal combustion engine altogether, which some companies are doing by switching to electric or battery-powered equipment.

Electric and battery-powered mowers run on motors, rather than engines, and tend to cost a bit more upfront than their engine-powered counterparts, says Joe Conrad, president of Mean Green Mowers.

“Electric mowers are going to be a higher initial investment,” he says. “Most contractors find that it takes about one-third of the service life to obtain the return on investment. The last two-thirds of the service life savings is money in the pocket of the contractor.”

Conrad says there are several reasons why landscape contractors may choose to switch to electric or battery-powered commercial mowers, including:

  • Customers requesting a green alternative that is nonpolluting;
  • Customers wanting quieter options; and
  • Contractors can more easily draw in new customers — or keep existing ones — by offering low noise and zero emissions.

According to Conrad, electric or battery-powered mowers also require less routine maintenance because they do not have belts, pulleys, hydraulics or oil that need changing.

“Electric mowers save money because of minimal maintenance and zero fuel to purchase,” he says. “They also save time since the mowers charge overnight and (operators) do not need to make trips to the gas stations during the day to fill up.”

Electric mowers’ lack of emissions is another upside for operators, according to Conrad. “Low noise, zero exhaust smells and very low vibrations mean less stress on the operator.”

Clara Richter

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