Advantages of the Diesel Engine

GENERAL INFORMATION

Modern diesel vehicles are attractive because of their ability to develop high pulling force at low engine speeds, which is especially good for drivers who do not like to shift gears too often. Most manufacturers offer turbocharged diesel engines so that the owner can fully experience the appeal of a high-class vehicle.

If you are considering switching to a diesel but do not know how to maintain it yourself, we can say right away that keeping a diesel in good condition is no more difficult than maintaining a gasoline engine, despite their differences. Below is a brief guide to buying, operating and servicing a diesel engine.

The mechanisms of gasoline and diesel engines differ little. Both engines operate on the four-stroke fuel combustion cycle, but this takes place in completely different ways.

In gasoline engines the air-fuel mixture is ignited by spark plugs, while diesel fuel is ignited by very high compression.

While a gasoline engine draws in air and gasoline on the intake stroke, a diesel draws in only air, which is compressed to such a degree that its temperature rises to 800 °C. The heated air ignites the diesel fuel, which is injected into the cylinder combustion chamber shortly before the piston reaches TDC on the compression stroke. Since the compression ratio of diesel engines is about twice that of gasoline engines, fuel must be injected at very high pressure so that it penetrates the combustion chamber and the fuel spray retains its shape. Because of these increased injection requirements, the diesel high-pressure fuel pump is a component manufactured to very high precision.

Older diesel models typically used in-line multi-plunger high-pressure fuel pumps. Now most modern diesels use more complex distributor-type rotary injection pumps with constant fuel delivery, since they work better at high engine speeds. Modern diesels use electronic fuel metering control systems to achieve a combustion process close to ideal. Many diesels are even equipped with catalytic converters to clean the exhaust gases.

There are two types of diesel engines, and the difference between them lies in how fuel combustion takes place. Some use direct fuel injection. The name itself indicates that fuel is sprayed directly into the combustion chamber cavity. Although this injection method is very efficient, its disadvantages are high noise and uneven running. For this reason, direct injection has been retained only on diesels used in commercial trucks. However, on engines of improved design these shortcomings have been largely eliminated, and most manufacturers offer highly efficient direct-injection diesel engines.

Other diesel engines, which do not use direct fuel injection, have a small additional chamber created in front of the combustion chamber into which fuel is injected. This chamber is located on the side opposite the injector mounting position and the direction of the fuel spray. This design solution allows higher engine speeds, but at the cost of some loss of power.