I was wondering the same thing...

 

I would say 2.5 is perfect!!! 3" is over kill

 

im not trying to argue, so everyone relax..
But so its everyone is just calling it luck of the draw that this shop is doing very well?

And ted, its not just one shop.. look into it more then one big name in time attack run at least 3" uicp (and they are well under the 1000hp mark)

Everyone seems to think its about volume, I think its more about airflow

 

You are making assumptions about what these people do or don't know. We've drawn conclusions from good faith testing from someone who cared enough to the invest time and resources to find the answer to this specific question.


That's because we understand that no matter what you do or how much power you make, you are still dealing with the volumetric demands of a tiny 2.0L engine.

If the difference between volumetric airflow and air density isn't clear, you will have a difficult time understanding much of this.

 

The decision between 2.5" and 3" should come down to RPM range and engine VE at the high revs. That's the only way your volumetric flow rate will get high enough to need the larger piping.

Your air density does effect frictional flow losses and I guess if you are real serious, you could consider that in your estimates. It's not 1:1 though and doubling boost pressure won't double your flow loss coefficients.

 

What about on a 2.4l engine ?