Diesel

 

 

 

The Difference Between a Two

and a Four Stroke Engine


There is one big difference between a two-stroke and four stroke engine, which is the amount of power the engine can produce. In a two stroke engine the spark plug fires twice as often (once per every revolution of the crankshaft) as in a four stroke engine (once for every two revolutions). This means that a two-stroke engine can potentially generate twice as much power as a four-stroke engine of the same size.

Some other differences are that two strokes are noisier, and they are considered less reliable and durable than four stroke engines.

The gas two stroke engine is not the same as the diesel that is because in a gas, some unburned fuel leaks out of the cylinder every time it is recharged. the diesel approach to the two stroke engine is far more efficient, and expensive, that the gas approach.

in a diesel two stroke engine  only air is compressed then fuel is injected directly into the compressed air which is much better than mixing air fuel and oil together and igniting it like in a gas two stroke engine. Many manufacturers of large diesel engines use this approach to make high-power engines.

At the top of the cylinder are usually four exhaust valves that open at the same time. There is also the fuel injector which has been developed and changed to ensure the fuel is distributed evenly. the fuel injector is one of the most secret part of a car and are kept company secrets.

The piston is longer than in a four stroke, so that it can act as the intake valve. At the bottom of the piston's stroke, the piston uncovers (usually) two air intake ports. The intake air is pressurized by a turbocharger. The crankcase is sealed and contains oil as in a four-stroke engine.

The Two-stroke Diesel Cycle

  1. 1.When the piston is at the top of its travel, the cylinder contains a charge of highly compressed air.

  2.  

  3. 2.Diesel fuel is sprayed into the cylinder by the injector and immediately ignites because of the heat and pressure inside the cylinder.

  4.  

  5. 3.The pressure created by the combustion of the fuel drives the piston downward. This is the power stroke.

     

  6. 4.As the piston nears the bottom of its stroke, all of the exhaust valves open. Exhaust gases rush out of the cylinder, relieving the pressure.

     

  7. 5.As the piston bottoms out, it uncovers the air intake ports. Pressurized air fills the cylinder, forcing out the remainder of the exhaust gases.

     

  8. 6.The exhaust valves close and the piston starts traveling back upward, re-covering the intake ports and compressing the fresh charge of air. This is the compression stroke.

     

  9. 7.As the piston nears the top of the cylinder, the cycle repeats with step 1.

The big difference between a diesel two-stroke engine and a gasoline two-stroke engine is  that a diesel two-stroke engine has none of the environmental problems of a gasoline two-stroke engine because only air is compressed, instead of a mixture of gas, air and oil. 

 

The Biggest Type of Diesel

Two-stroke Engine


The biggest type of diesel two-stroke engine were introduced in the 1930s by General Motors.  These engines are the most commonly found engine in modern diesel locomotives. 

A typical horsepower rating for one of these engines is 4,300 hp!

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