Sharon J. Rehana
Sharon J. Rehana

There are two main differences between a diesel and a gasoline engine. A diesel engine takes in air, compresses it, and then injects fuel into the compressed air. The heat of the compressed air lights the fuel spontaneously. A gasoline engine intakes a mixture of gas and air, compresses it, and ignites the mixture with a spark. The second difference is in the rate of compression. A diesel engine compresses at a ratio of 14:1 to as high as 25:1, where a gasoline engine compresses at a ratio of 8:1 to 12:1. Choosing the right engine depends on the type of application. According to Brad Murphy, vice president of sales and marketing for Robin America Inc., Wood Dale, Ill., “Both diesel and gasoline engines have advantages and disadvantages. If the equipment is being used continuously, then a diesel engine is probably better because you can get more mileage and fuel use out of it. However, a diesel engine is more expensive to purchase and maintain than a gasoline engine.” Murphy claims that small engines in North America are primarily run on gasoline due to cost and EPA regulations. In fact, few companies produce small diesel engines for the North American market.

Briggs and Stratton Vanguard 3LC Turbo Diesel engine
Briggs and Stratton Vanguard 3LC Turbo Diesel engine

Briggs and Stratton Commercial Power produces the Vanguard 3-Cylinder liquid-cooled diesel engines that are lightweight and reduce soil compaction. Available in 23.6-, 25.6-, 31-, and 34-hp models, the liquid cooling provides cleaner combustion and meets emission regulations.

Most companies, however, provide gasoline engines for light construction equipment. Kohler offers the Command PRO 40-hp OHV engine, available in horizontal- and vertical-shaft configurations, the new engines target a range of commercial and industrial applications. Featuring an overhead valve design with an electronic ignition system, two-barrel carburetor, and mechanical governor, the engine uses an aluminum block with cast-iron cylinder liners.

Subaru EX27 engine
Subaru EX27 engine

The EX Series of engines by Subaru is designed with a chain-driven overhead cam (OHC). “The technology used is similar to the engine technology used in cars,” says Murphy. “The overhead cam provides a consistent and quieter engine.” The OHC technology allows the intake and exhaust valves to be positioned for optimum engine performance, offering lower resistance for the air/fuel mixture flow.

Although diesel engines provide more mileage and are more fuel-efficient than gasoline engines, the cost may not be justifiable for smaller applications. To see a comparison of diesel and gasoline engines click here.

You can contact Associate Editor, Sharon Rehana, at srehana@hanleywood.com