Start Your Engines

Tim “The Tool Man” Taylor from the mid-1990s sitcom Home Improvement strikes a chord as the ubiquitous man’s man. He grunts as a means of communication. He derives excitement from tools. And most of all, when it comes to cars and equipment, he desires speed and power – the faster and stronger, the better.

Landscape contractors, like thousands of Tim Taylor clones across the country, also recognize the “need for speed.” The faster the mower, the better – the more horsepower, the better. And a mower that can zip quickly across lawns while delivering a quality cut is as valuable to landscape contractors as the hot rod is to Tim Taylor.

Fast, powerful mowers do more than wow their owners, however. In the green industry, time is money, and an efficient, effective mower spells success. Yet, just as the hot rod is merely a pile of metal without the workings under its hood, a mower’s lifeline – its engine – lies beneath the deck.

Depending on the contractor’s budget, property requirements and personal preference, the right combination of cooling, fuel systems and maintenance requirements spells productive property management. Manufacturers usually provide guidance as to recommended mower engine requirements, but some contractors desire that extra oomph, noted John Chiera, national turf account manager, Briggs & Stratton, Milwaukee, Wis. “Manufacturers have traditionally powered their equipment correctly,” he said. “But contractors want speed – just like Tim ‘The Tool Man’ Taylor.”

WALKING ON AIR. An overheated engine is an unhappy engine – high heat stresses the engine and shortens its overall life span. Therefore, an engine’s cooling system plays a large part in success in the field. Engine cooling can be accomplished through a fan system in an air-cooled engine, or water surrounding the engine in a liquid-cooled system.

Historically, the primary option for mower engines was an air-cooled system, Chiera related.  However, over the past few decades, contractors’ appetite for increased horsepower spurred a two-cylinder air-cooled engine. “Productivity in the contractor’s mind is not necessarily, ‘How do I do it better and more efficiently?’” he said. “It’s, ‘How do I do it faster?’”

As a result, air-cooled engines expanded with added overhead valve configurations and design technology improvements. Increased Environmental Protection Agency (EPA) emissions regulations also drove updates in air-cooled technology, Chiera said.

Paul Blum, product manager for single-cylinder engines, Kohler, Kohler, Wis., added that in the past, engineers worried that EPA emissions regulations would force the industry to make a complete switch to liquid-cooling engines. “But that has proven so far not to be the case,” he asserted. “Air-cooled engines have been able to meet all the emissions regulations to date.”

In addition, choosing air-cooled engines historically meant choosing a lower horsepower, related Cam Litt, product manager for twin-cylinder engines, Kohler. “It used to be that with higher horsepower, contractors used liquid-cooled,” he said. “Now, air-cooled engines are catching up, and you’re seeing them in applications above 20 horsepower.” He also pointed out that the overall package size of air-cooled engines is smaller than liquid-cooled engines, so tight spaces and smaller applications are better served by air-cooled systems.

Despite improvements, air-cooled engines inherently provide challenges, said Randy Lockyear, sales manager-turf and outdoor equipment manufacturer, Kawasaki, Grand Rapids, Mich. “Air-cooled engines mean that certain parts of the engine are hotter than others,” he explained. “Also, on air-cooled you have more shielding around the engine near the cylinder heads, and the fans can easily plug up with grass.” Fans full of grass cause the engine to overheat, and eventually fail, Chiera added.

Likewise, air filters have to be cleaned regularly, sheet metal housing must be removed for cleaning, and dust and debris have to be frequently blown out of the cooling area, all resulting in substantial maintenance for air-cooled systems, Chiera noted. Although some improvements have been attempted to maximize the cooling effects of the fans, such as changes to the manner in which the sheet metal is mounted on the engine, the air-cooled technology still has its limits, he concluded.

COOL IT. Power-hungry contractors do have an alternative – liquid-cooled engines. These engines feature longer life expectancy, the opportunity for enhanced horsepower and more efficient fuel economy – but with a trade-off. Liquid-cooled engines also come with a higher price tag, Chiera pointed out. “Liquid-cooled engines provide greater horsepower and they’re more efficient because they run cooler,” he said. “But when you add all the extra components, you also add cost in the 30-percent range.”

However, in some contractors’ minds, the benefits may outweigh the additional cost, Lockyear explained. Liquid-cooled technology cools the engine more effectively because the water running through the engine takes heat away from the “hot spots” of the engine. “The liquid dissipates the heat a lot better than air,” he said. “The liquid-cooled stabilizes heat, which places less stress on the engine. The engine will last longer and it’s a more consistent and efficient way to cool the engine.” Further, lower temperatures prevent the oil from breaking down as quickly, which lengthens intervals between servicing and, thus, saves contractors money, Litt remarked.

Chiera referred to Briggs & Stratton’s design life tests as key indicators of liquid-cooled advantages. During the test life, engines are tested 24 hours a day, 7 days a week, until they stop running. “Our current air-cooled engine has a test life in the 1,500-hour range,” he said. “But our comparable liquid-cooled engine is in the 2,500-hour range.” This 30 to 40 percent increase in life span is due to the engine’s efficiency, in terms of fuel consumption and improved heat dissipation.

And, since contractors do not realistically run their mower equipment on a nonstop basis, the engine’s life can potentially be longer, as long as the engine is maintained properly, he continued. In some applications, this can translate to an engine life of 4,000 or 5,000 hours, Lockyear suggested.

Since liquid-cooled engines run leaner than air-cooled engines, not requiring as much fuel, the fuel efficiency and reduced emissions are strong selling points, Lockyear said. Also, the water surrounding the combustion chamber absorbs excess sound, resulting in a quieter engine.

Despite the liquid-cooled benefits, this engine type has its downfalls, most notably, price. Liquid-cooled engines also tend to be heavier, Blum said. “If you don’t have some sort of radiator in the engine, you have to put coolant in it, which is an added cost,” he stated. “Overall, with liquid-cooled you’re more expensive if you have a higher horsepower. It’s just a higher-end machine.”

Yet, Chiera claimed that when contractors measure the advantages against a higher price, they’ll choose liquid-cooled for its competence. “If you take the additional engine life and fuel efficiency and divide that out over the life of the engine, it’s easy to say that you can justify the additional expense.” And, Blum maintained that both air-cooled and liquid-cooled serve as healthy alternatives to one another, balancing out the other’s flaws. “What is a negative for liquid-cooled is a positive for air-cooled, and vice versa,” he noted.

FILL ‘ER UP. As if cooling systems weren’t enough for landscape contractors to debate when selecting mower engines, they must take a look at gas-powered engines vs. diesel models. In terms of engine life, diesel engines will last far and beyond gas-powered engines, Chiera stated. “Liquid-cooled diesel engines will live many more hours than a liquid-cooled gas engine – in the thousands of hours,” he said. “Of course, the biggest advantage with liquid-cooled diesel is it offers 50-percent additional fuel economy. It will go twice as far on a gallon of fuel.” Diesel engines provide more torque in a machine that typically runs at more than 50 horsepower, Lockyear added.

Diesel technology for mowers proves especially beneficial for contractors who already run a variety of diesel-powered equipment, such as trucks, Litt said. But as a rule, diesel technology has yet to catch on with the common contractor, Chiera admitted. “The commercial contractor doesn’t necessarily understand all that value. Again, he’s looking for horsepower,” he noted. “In fact, the only time you’ve seen a trend toward liquid-cooled diesel is if the cost of fuel goes up.”

When gas shot above $2 in the summer of 2001, commercial cutters made a brief move toward diesel, he continued. But fuel costs under $1.50 eliminate any driving force toward diesel. The opposite is true in Europe, where contractors choose diesel because of high fuel prices, Litt said.

However, municipal and government landscape maintenance creates a niche for diesel-powered mowing equipment, Chiera said. “They use primarily diesel equipment, so they understand the benefits of diesel power,” he explained. Plus, for the average landscape contractor, the improved life span of diesel power becomes a downfall because the engine outlives the equipment. “Because their equipment is extensively used, they caution on the side of going to liquid diesel because the engine can outlive the chassis of the machine,” he said. “They depreciate equipment so quickly.”

Diesel engines also have yet to live up to some of the strict emissions regulations currently dictating engine requirements in the green industry, Chiera said. But he believes that diesel offers promising potential for manufacturers, despite current design and manufacturing costs. “If you can increase engine life 30 to 40 percent and increase fuel efficiency 20 to 30 percent, all in a compact package that’s easily mounted in pieces of equipment – that presents a tremendous opportunity,” Chiera explained.

Yet, Blum suggested that at times, diesel advantages can be attributed to perception and, again, the “right” choice lies in contractors’ needs. “Diesel has a higher upfront cost, heavier weight but a longer life than a gasoline engine,” he said. “However, we have some gasoline engines that, from reports, have proven to have a life span that is up there with diesel.”

Of course, savvy mower engine consumers should listen carefully to manufacturers and dealers when purchasing equipment, Chiera noted. “Take your requirements to a very knowledgeable equipment dealer and take their recommendations to heart,” he said. “Size the engine to the application, take a look at upfront cost, projected maintenance cost, fuel costs and your required life expectancy, and see if you want to invest in the product.”

On the other hand, the Tim Taylors of the world will always value power and speed over practical considerations such as life expectancy and fuel costs. As long as contractors select a mower engine that can accommodate their properties and business needs, they can be guaranteed a smooth ride, Litt reminded. “It completely depends on people and their applications,” he said. “There’s not a right or a wrong answer.”

The author is Assistant Editor – Internet of Lawn & Landscape magazine and can be reached at kmohn@lawnandlandscape.com.