Four stroke engines are widely used in automobiles today. Understanding of a four stroke engine is important. Below are some advantages of four stroke engines.
Fuel efficiency was one of the reasons four stroke engine is preferred over its rival two stroke engine. In a four stroke engine, all the strokes are clearly defined and discrete, so complete combustion of the fuel happens. This leads to fuel being used completely that is charged in.
Long life and durability
Over its two stroke counterparts, four stroke engines have better durability and a long engine life. The four stroke engines revolve a less number of turns since it has to maintain less RPM. This leads to lesser wear and tear of the engine thereby increasing its life. A two stroke engine is rated for high RPM. Thus greater the wear and tear and less life of the engine.
A four stroke engine has to do undergo four strokes for a single power stroke, whereas a two stroke engine can do it only in two strokes. So a four stroke engine produces less power than a two stroke engine. But due to complete combustion of fuel and systematic stroke action, four stroke engines have more torque even though the RPM produced is less.
Quieter and clean operation
A systematic and consolidated full-fledged action of four discrete strokes ensure that fuel is completely burnt in the cylinder. Additionally, a separate system handling the lubricating oil ensures that only fuel is burnt in the cylinder. This leads to quieter and cleaner operation. In two stroke engines, lubricating oil that is mixed with the fuel also undergoes combustion that leads to spilling out of oil and unburnt fuel. This makes the operation dirty and noisy.
Conventionally, engine was classified into two stroke engine and four stroke engine depending upon the number of operations required for the operation of the engine. Though two stroke engines produced almost double the power, they have become obsolete over the time due to few disadvantages. Though the four stroke engine was complicated in design and manufacturing, it survived because of the advantages.