Now that I have this borg warner s472 turbo which has a 3.5" air outlet, how bad is it to have 2.5" intercooler piping? Should I upgrade to at least 3" or should I be fine with 2.5"? THanks.

 

I would run the matching diameter on the compressor side and reduce (keep the same size currently) the diameter on the intake side to help with pressure drop.

~S~

 

alright I'll do that, by chance, what would happen if I ran the 2.5"? Just never thought about it till now.

 

Nothing really, it would just be a bit restrictive for the compressor side. In a perfect world ideally it is good to match the compressor side then step up a bit before entering the end tank, on the IC discharge side step it down a size to pick up some pressure loss, all this should help with response. So run the 3.5" tubing on that side then run either your 2.5", 2.75", or 3" on the discharge as all would work pretty good.

~S~

 

Cool thanks man, I appreciate that. Would like to do everything possible to help out with response as this turbo is quite beastly. I really wanted a fully divided manifold for this but I guess this manifold will have to do for now.

 

Ok. Ok. Here we go. I will first start by checking my 4" exhaust thred. DO NOT REDUCE PIPING SIZE FOR THE AIR ENTERING AND LEAVING THE INTERCOOLER, run the 3.5" piping on both sides. I have the dyno chart to prove I know my s--t. I actually steped my system up from the turbo's 2.5" to 3.5" piping I'm using on both sides. See the link.
https://www.rx7club.com/single-turbo-rx-7s-23/4-complete-exhaust-system-build-770041/page8/

 

There is zero need for 3.5" piping on the discharge side, ZERO need, especially coming out of a IC for his setup, I've ran over 860whp on 3" tubing. I don't have dyno sheets though and I'm still learning. I do have a pic of said car though.

 

lol what a coincidence I've had my car tuned (well at least half way) by frank at world wide. Good guys over there. Well I'm not going for highest hp in the world, I'm really more concerned about response so if stepping it down after the intercooler will help out in this area then I don't mind if it takes a bit of hp off the top...