Intercooler Inlet/outlet Diameter

[NoJokE]

What inlet/outlet diameter is best for an intercooler? 3" for both or 3" inlet/2.5"outlet?

 

[posol]

3" is way too big for most setups.

average is 2 1/4

 

[JDMSpecAccordSir-T]

yeah i've only heard about 3 inch oulets on cars making 1000 hp or more (Skylines Supras). And dont quote me on this one but piping diameter (you would have to go full 3 inch for all the intercooler piping also) has alot to do with the velocity (speed) of the air much like an exhaust system.

In general this is how it works

bigger piping=more air slower=more lag/less responsive/higher HP potential
smaller piping=less air faster=less lag/more responsive/lower hp potential

Unless you have a need for it, it can cause severe lag unless you have a big enough turbo or running very high boost levels (20+ psi).

Like pissedoffsol said you probably woulnt need to go over 2 1/4 for a Honda. Most people get 2 1/2 because its readily available and leaves room to upgrade

 

[posol]

actually, most intercoolers- even the big ones like the skyline spearco's, are 2 1/4.