IC pipe sizes

Facime

Leather work expert
Jun 1, 2006
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Corvallis OR
ok, Im trying to sort out what the previous owner did to this car, and Im a little confused and need the wisdom of more turbo savy people.

My question is about using different diameter IC pipes and their effect on air volume and speed. The outlet off the CT-26 is 2". My first question is would it make any difference to have larger pipes anywhere else in the system since this initial outlet is going to be the limiting factor? Looking at the other end of the system, there is a 2" restriction on the 3000pipe as well, so my guess is that running ANY larger sized piping anywhere in the system without removing the 3000 pipe restriction would be useless.


So, for my specific application, I have mated a 2.25" hard pipe to the turbo outlet using an old piece of the original soft pipe as a coupler. From there it couples up to a 3" aluminum pipe before crossing over in front of the radiator. the FMIC has 3" in and out, and on the cold side there is a short 3" piece with my BlitzBOV mounted on it. It then couples down again to the stock fender pipe and remains stock all the way to the TB.

The problem is that the 3" pipe that crosses the front of the nose to get to the left side of the FMIC is too big to tuck up properly. Also the stock fender pipe and remaining system is restrictive I know, and I was thinking about fabricating some 2.25" or 2.5" hard pipe for that. So I guess what Im asking is will 2.5" pipe actually make ANY difference over 2.25" ?

Last question, what effect does the 3" in and out on the FMIC have in the equation. my guess is that it is neither a good nor a bad.

Please discuss IC piping and what you know about it.
 

Mr.PFloyd

I am the Super Devil
Jun 22, 2005
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Mississauga, Ontario
2 inch IC piping is more then enough for the stock turbo. i have heard peoel runnign too large IC piping on the stock ct and causeing compressor surge (im pretty sure thats what the whoel arguement was about) but if you 2.25, im sure you will be fine in comparison with 2.5 i think that with the stock ct, 2.5 is useless.
 

Facime

Leather work expert
Jun 1, 2006
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Thanks for the links, But really my question was kinda lost in my rambling.

What Im trying to ask is...If Im leaving the stock piping on the cold side, would it do any good to have larger piping on the hot side? My guess is NO, but wanted to ask anyway.

But, it kinda doesnt matter now, as I was anxious to tuck the piping up closer to the radiator before I ripped it off on some road hazard. So I ended up going with 2.25". When I get to changing out the cold side piping I may do something different then. Thanks for the replies.