Intercooler Piping, 2.5 or 3" Options

[NEVERSTOP]

well whatcha think.. should I use 2.5 or 3" piping for my FMIC? have really been goin back and forth over this for months and really dont know what to do.. Think with 3" I would probably have better results but dont wanna slow down the airflow...

Opinions please

[1bwilson]

2.5.............3" is going to create hella lag on the turbo. If you were to do a good P&P on the head and maybe a nice intake manifold then I would use 3" but I go with the best turbo--> IC--> TB match as possible. A good thing to ask yourself is what size inlet/outlet is your IC?

-Bryan-

[NEVERSTOP]

IC 2.75 TB 3"(aftermarket one) Believe turbo is 2.75 also.. thats part of the reason I'm leanin towards 3" but I dont want to comprimise things.. but am worried about if I got smaller im gonna break something

[1bwilson]

I think the ct26 is more like 2.25"

-Bryan-

[NEVERSTOP]

your probably right on that... I havent measured it

Wonder if I could run 2.5 down to the IC and then run it threw an expander right before the IC and then run 2.75 right up to my BOV and 3 after that to my TB... kind of a gradual increase of the amount of air per square inch.

I know that with how my intercooler is set up I will not loose alot of air speed running threw it like a taller intercooler will... so If I lose a speeed on the air with the piping it will kinda balance out a little...

Who knows I'll figure something out... Hell I just use a buncha straws taped together

[DG_Performance]

I would run 2.25" or 2.5" piping all the way around.
3" is way too big for the application you are going to have
the outlet of at ct-26 is only 2" ... the inlet is 3" but that is to allow the turbo to pull whatever amount of air it needs without restriction!
when the turbo spulls up you want the flow to quickly pressurize in the ic piping! unless the turbo outlet is bigger than 2.5" you are kinda defeating the performance of the turbo by making the piping way too big
2.5 " is deffinetly big enough for whatever boost you plan on running in any 4 cylinder street legal car even if it is sicko fast.
Like bwilson said try to stay as close to the same size as the TB. reducers can be used for your intercooler but most all that would be good on our cars are about 2.5 inlet and outlet!
Another downside to 3" is cost and where to run it (3" is huge and bends are wide you will never get it to fit where you really want to run it without hacking you car all up)

Even some places that tested high performance downpipes for the 3sgte only run 2.75" piping with like 1% difference in performance compared to the 3".

I make custom intercooler piping and exhaust piping and i only use 2.25" or 2.5 in piping depending on the application!!!!!!!

Do what you want to ...but it is my honest opinion to stay away from the 3"
Good luck whatever you decide!
DG

[5sfeTurbo]

Whats a good dimension for a FMIC(on a 5s if it matters) probablly the same though. Anywho I was always told that 2.5 was more than enough as well. But you are really trying to eat it up at the same time, so do you think you would really be hitting the internals and then slapping on a fatter turbo..?...what is your final goal, if there's logically ever an end to the madness

[NEVERSTOP]

well my final goal is kinda heading in a few different directions.. If I go back to the 205 top end then I will probably leave it single turboed and upgrade. I am currently thinking about using those two turboes Im pickin up from dg to setup a twin turbo setup but that means I have to stay with the 185 topend which I do not know the performance of it yet compared to the 205 topend - but TVIS intrests me so I wanna try it out for a while.

I would personally like to run the twin setup for the quick spool time at lower boost per turbo... that and it would be cool to have a twin turboed celica - but thats gettin off the subject.

I have JE pistions, HKS cam shafts and gears.. If I change the turbo, either upgrade or twin I am gonna redo the head and probably have the crank turned at that time

I have a really good reaction time off of the line.. doesnt matter what I drive so If I have a little bit of spool time then thats fine cuz I can make up for it some but It is a good point about increase lag time and one well taken

The problem is there are alot of different sizes in my set up like I said a few posts
up.. Turbo 2-2.25 which ever it is FMIC 2.75 TB 3"

I would rather have the air move at the same speed the whole way threw than have it speed up and slow down along its course... I probly will do something in the area of 2.5-2.75... just worried about that TB inlet.. heres a pic to show you what I am talking about cuz theres a couple inches of it and I dont know how keen I am about the air slowing down at the last minute..

well imagestation is currently down so I will post the pic later

edit: 5sfeTurbo hit this guy up on aol/aim TJN115.. there might be a space in it like this TJN 115 but can't remember.. he makes intercoolers that are perfect for the celi and there pretty resonable on the price 230ish

This post has been edited by NEVERSTOP: Dec 7, 2003 - 10:18 AM

[NEVERSTOP]

okay went and took measurements.. Turbo outlet ID 1 5/8 inch.. IC inlet and outlet ID 2 1/4 TB inlet 2 1/2.. so think I will go with 2 1/2 and just leave it at that and hope I dont pop a connector or anything

[DG_Performance]

Neverstop,
You brought up something i was wondering about !!! What are all the known differences between the 2nd gen and 3rd gen motors??? I know the intake is different and the head is a little different but what are all the other differences? Is there a bunch of other things? I have not had time to research this yet and you could save me some time if you know the answer to this question!!!
thanks ,
dg

[98celica3]

would 2" be too small?
adam
i am only gonna run 10psi at the most

[Kwanza]

[zipstrips]

im running 60mm pipes.. like 2inches. no lag, no heat soak either... get couplings to step up or down to the sizes u need.