What if you fill diesel in a petrol car? | The Mechanical post

Engines are the heart of conventional automobiles. The majority of automobiles work on either petrol or diesel. So What if you happen to fill diesel in a petrol car? Let’s find out.

Note: It is highly advisable NOT to try such things.

What will happen if you fill diesel in a petrol engine?

If diesel is filled in a petrol engine, the combustion process would not take place and the automobile would stop working. If diesel is filled in the tank of a petrol car, it would run for a while normally until all the previous petrol in the tubes is consumed  

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Then as the diesel would start entering the engine, your car would stop. How ?? let’s see.  

Petrol is a fluid that has a lower flashpoint. This means that it takes a comparatively low temperature for petrol to detonate or burn.  Thus the compression ratio of petrol is low (about 6 to 10.5) ie. in short the volume of the cylinder which houses the piston is less, resulting in less pressure development during compression.   

As the petrol engine’s compression ratio is low, during compression the petrol and air mixture doesn’t ignite. Thus a Spark plug is used to ignite the air-fuel mixture. Diesel unlike petrol has a higher flashpoint. Thus it takes a higher temperature for diesel to detonate or burn. 

Diesel engines are constructed with a higher compression ratio (around 14 to 22) which means the cylinder which houses the piston has more volume and the stroke length of the piston is more.   

Therefore during the compression cycle of the engine, the heat due to compression-only becomes so intense that the air and fuel mixture gets ignited without the need for a spark plug.
Petrol engines have a low compression ratio and diesel fuel has a high flashpoint. This means that, due to the low compression ratio of the petrol engine, the diesel won’t get enough heat to ignite. 

Also, the diesel would clog the spark plug which will only add to the cost. Since there is no combustion produced, there would be no power developed and the automobile won’t advance.

However, you would need to remove all the diesel from the tank, tubes and engine to get your car working. This process would be expensive.

Therefore, never ever fill your car with the wrong fuel.