Types Of Strokes

A diesel engine can be broadly distinguished as two-stroke and four-stroke. Bulky engines usually operate on the two-stroke cycle. Lighter engines generally operate on a four-stroke cycle. Generally cylinders are used in multiples of 2, 4, 6, or 8. It doesn’t matter what number of cylinders are being used as long as the load on the crankshaft is counterbalanced to prevent excessive vibration. The in line 6-cylinder is used widely in medium and heavy duty engines.

There are three basic size groups of diesel engines based on power—small, medium, and large. The small engines have power-output values of less than 188 kilowatts, or 252 horsepower. This is the most commonly produced diesel engine type. Used in automobiles, light trucks, and some agricultural and construction applications, they also serve as small stationary electrical-power generators (such as those on pleasure craft) and as mechanical drives. They are typically direct-injection, in-line, four- or six-cylinder engines. Many are turbocharged with after coolers.

The most outstanding feature of the diesel engine is its efficiency. By compressing air -- rather than using an air-fuel mixture -- the diesel engine is not limited by the preignition problems that plague high-compression, spark-ignition engines. Thus, higher compression ratios can be achieved with diesel engines than with the spark-ignition variety; commensurately, higher theoretical cycle efficiencies, when compared with the latter, can often be realized. For more information about diesel engines, visit Depco's web site for more details.