Just curious, I've seen setups from 2.5" up to even 3.5", is there even a difference besides some lag because there is more volume to fill before the manifold is pressurized? How much power would you have to make before your charge pipe diameter limited you at 2.5"?
thanks for the input,
Jared

 

I'm sure 2.5" piping can handle WAY past 600hp, so bigger than that is pretty much overkill for most setups.

Most people will just choose the piping that best fits the TB to make a smoother flow into the intake mani.

Another trick is to do 2" from the turbo to the intercooler, and then 2.5" from the IC to the TB. This cuts down on lag, and makes the IC a little more effiecent.

 

i thpought it was 2.5 till the ic, then 2" past that, to keep pressures the same. same idea is used in a/c ducting in homes. when theres a vent, they shrink the pipe by one inch on 2 sides, resulting in no pressure loss. maybe how my kooky head works tho..

 

remember, heating ducts are venting to the atmosphere, where as a turbo is compressing air into an engine.

Most compressors have a 2" outlet (T4, T3, T-25)...ect. The 2" initial piping will keep a straight turbulent-free flow of air into the IC. Because the piping is so small the air will begin to cool as soon as it exits the piping. (just like when you spray something from a can). This will help the intercooler do it's job more effectivly by getting rid of heat even before it enters the heat exchangers. From there the air won't be heated up as much when it's compacted back into the 2.5" piping because it's larger than the 2" pipe. It just so happens that most Honda TB's are 2.5" diameter, so this combination works out very well.

 

ohhh, i get it now...