Pipe Size Physics

Hello all...

I have a kind of basic but complicated question.

If you use a reducer to change pipe sizes, from say 3.0" to 2.5" will that cause the pressure in the 3.0" section to increase, while the pressure in the 2.5" section will be unusually low do to the increased velocity?

And then if you went back out to 3.0" after the 2.5" section will that would cause the pressure to rise again, even though you are filling up a larger volume?

And would the pressure in the second 3.0" section still be lower than the pressure in the first section, due to the chocked airflow?

Does that sound correct to you?


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High P``` Low P`` Mid P ```----> Flow
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Quote:

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Originally Posted by Static

Hello all...

I have a kind of basic but complicated question.

If you use a reducer to change pipe sizes, from say 3.0" to 2.5" will that cause the pressure in the 3.0" section to increase, while the pressure in the 2.5" section will be unusually low do to the increased velocity?

And then if you went back out to 3.0" after the 2.5" section will that would cause the pressure to rise again, even though you are filling up a larger volume?

And would the pressure in the second 3.0" section still be lower than the pressure in the first section, due to the chocked airflow?

Does that sound correct to you?


------------ ``````------------
````````---------
High P``` Low P`` Mid P ```----> Flow
````````---------
------------ ``````------------

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No. While i'm not dragging out my old textbooks,lol, the velocity increase across the outer wall surface of the lesser diameter is not going to make the pressure in that section "unusually" low. Maybe just a skosh.

While the flow would then slow down as the piping opens back up, the psi reading on the gauge is going to come from whatever restriction is beyond the tubing.

Your intake/heads/valve size/cam timing is going to be deciding factor of what that gauge reads.

disclaimer: anyone smarter than myself is hereby authorized to prove that i may be talking completely out my ***.

the mean (average) air pressure will remain the same as a end product of the blower and resistance (boost) to flow, what will change is air speed, the air will speed up in the contractions and slow in the expansions. there will be small local pressure changes but they will be small and will be reduced and eliminated as you create and increase boost