So this one puzzles me. It seems pretty common for people to go up in size a little on the cold side of their FMIC. Which doesn't really make any sense to me since the cold air is denser and takes up less space. Is it a convenience thing? Are people just matching the TB size and turbo size respectively? Or is there something I'm missing?




Listen F***ers. FASTERTHANAHONDA is a joke because I WORK FOR HONDA. I'll talk @!#$ about Fords to, that doesn't mean I can beat a 12 second mustang.

some people keep the hotside smaller to help increase spool. And iirc keeping the cold side a little bigger helps flow, colder air in faster is a positive.



LE61T PTE6262 Powered

So are you talking about the "entrance" being smaller than the "exit".
When I made my intercooler, I used 2.5" for both.
Personally, I have never seen a fabricated intercooler with 2 different sizes, but that doesnt mean they dont exist.

It is a velocity thing, as Phil notes. Like a stepped header, having the sizes get progressively larger as the air makes its way from the turbo to the throttle body allows the optimal combination of flow and velocity. Additionally, as most turbos have a compressor outlet that is considerably smaller than throttle body hose size (usually 2" vs. 3", a common example), this makes for a handy size-up transition without having to use too many stepped couplers or stepped piping.



Bill Hahn Jr.
Hahn RaceCraft

World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com