Questions

[Cephalopod]

What is the average concussive yield of a basic combustion chamber in average car. The PSI of the explosion if you will. If the same amount of gas is applied what is the maximum possible size/ shape of the chamber in the engine?

 

 

Thank you.

Edited December 22, 2016 by Cephalopod

[swansont]

I think you need to provide the details of the average car's engine before you can apply physics to it. How much gasoline is being combusted? How big is the chamber? Then you can take the enthalpy of combustion (~45 kJ/g) and apply some thermodynamics to it.

[Cephalopod]

I think you need to provide the details of the average car's engine before you can apply physics to it. How much gasoline is being combusted? How big is the chamber? Then you can take the enthalpy of combustion (~45 kJ/g) and apply some thermodynamics to it.

I need to figure out the largest possible size of the chamber. It's probably different per vehicle.

[Cephalopod]

scientific community? Where's the community part?

[steveupson]

Here are some basics for you, and maybe you can refine the question a little to get a better response if this isn't what you need. The size of the combustion chamber for a given engine can be calculated if you know the displacement, number of cylinders, and the compression ratio. The combustion chamber size is a measure of its volume.

 

The compression ratio of an engine is the volume of the cylinder when the piston is at bottom dead center (maximum volume of the cylinder) relative to the volume of the cylinder with the piston at top dead center. The volume at top dead center is the minimum volume of the cylinder, and is also the volume of the combustion chamber. In other words, the size of the combustion chamber is the volume of the cylinder when the gas charge is fully compressed at the top of the stroke.

 

We have a four-cylinder two-liter engine. Each cylinder displaces 500cc during a stroke. If the compression ratio is 10:1 then you know that the combustion chamber is 50cc.

 

Typically, engines in street cars have compression ratios ranging from about 8:1 to 10:1 although there are still many that fall outside this range. A typical diesel might be 14:1 to 18:1 because it needs a lot more compression which will raise the temperature of the fuel/air charge to the point where it ignites.