2.25 is a rectriction @ 450whp no matter what yout tuner said. H-T had a good thread where it showed CFM requirements at different PR's and while you are ok, you would pick up spool and some power keeping all 2.5" piping. Just saying.

 

Okay way to be a dick, I was just pointing out that it's not a godspeed intercooler in that pic mounted on the car, it has cast end tanks and more densely packed fins than the cheapo one that many people use and think are great.

Anyway, You do want the smallest IC piping as possible for your setup that is able to handle the amount of air you are moving. If the piping is too small, flow will become turbulent. If the piping is too large, yes it can handle the flow, but boost response time will increase.

The velocities are in miles per hour and mach, and the flow rates are in cfm. Measurements for the piping are in inches.

0.4 mach = 304 MPH

2" piping
1.57 x 2 = 3.14 sq in
300 cfm = 156 mph = 0.20 mach
400 cfm = 208 mph = 0.27 mach
500 cfm = 261 mph = 0.34 mach
585 cfm max = 304 mph = 0.40 mach


2.25" piping
3.9740625 sq in = 1.98703125 x 2
300 cfm = 123 mph = 0.16 mach
400 cfm = 164 mph = 0.21 mach
500 cfm = 205 mph = 0.26 mach
600 cfm = 247 mph = 0.32 mach
700 cfm = 288 mph = 0.37 mach
740 cfm max = 304 mph = 0.40 mach


2.5" piping
4.90625 sq in = 2.453125 x 2
300 cfm = 100 mph = 0.13 mach
400 cfm = 133 mph = 0.17 mach
500 cfm = 166 mph = 0.21 mach
600 cfm = 200 mph = 0.26 mach
700 cfm = 233 mph = 0.30 mach
800 cfm = 266 mph = 0.34 mach
900 cfm = 300 mph = 0.39 mach
913 cfm max = 304 mph = 0.40 mach


2.75" piping
5.9365625 sq in = 2.96828125 x 2
300 cfm = 82 mph = 0.10 mach
400 cfm = 110 mph = 0.14 mach
500 cfm = 137 mph = 0.17 mach
600 cfm = 165 mph = 0.21 mach
700 cfm = 192 mph = 0.25 mach
800 cfm = 220 mph = 0.28 mach
900 cfm = 248 mph = 0.32 mach
1000 cfm = 275 mph = 0.36 mach
1100 cfm max = 303 mph = 0.40 mach


3.0" piping
7.065 sq in = 3.5325 x 2
300 cfm = 69 mph = 0.09 mach
400 cfm = 92 mph = 0.12 mach
500 cfm = 115 mph = 0.15 mach
600 cfm = 138 mph = 0.18 mach
700 cfm = 162 mph = 0.21 mach
800 cfm = 185 mph = 0.24 mach
900 cfm = 208 mph = 0.27 mach
1000 cfm = 231 mph = 0.30 mach
1100 cfm = 254 cfm = 0.33 mach
1200 cfm = 277 mph = 0.36 mach
1300 cfm max= 301 mph = 0.39 mach


So 2.25" can flow 700cfm safely, which is a lot of air.

An HKS GT3037: uses GT37 76mm 52trim compressor. 70mm housing inlet.
And it can flow 49 LB/Min or 709cfm max flow @ 2.4PR @ 60% efficiency with
33psi max boost limited by compressor wheel speed.

What's that, around 500hp range? So I don't think that at 450whp 2.25 is much of a restriction. So his tuner was correct if you want to look at it this way.

btw since i'm only a guest, you can ignore all this if you want.

 

very good info.

the Intercooler itself looks great and pretty big. here is a quick pic



idk guys my thoughts are to make 350-390 rwhp. then go from there. I know my turbo is good for 500+.

just wanna have it set up like this till i get a better clutch and build the rear. once that happens ill drop the compression and make the other changes. but for now i think w/what i have i can make 375. well c though.

 

someone on HT still picked up power with all 2.5" piping over 2.25 at a lower power level. Cant recall who it was however.

 

Without anything being changed? Same routing and all? Remember they could have removed some bends, shortened the piping, fixed a leak they had and were unaware of, changed the tune etc etc. I was just stating the numbers

 

And don't get me wrong, I'm not totally against the cheap ebay copy intercoolers. I use one on my civic. But would I ever use it on my S? no. I have a nice precision 750hp IC which has great construction, which will help to cool the air going into the engine. And cooler air will make more power.
The civic was the budget build turbo setup, the S is the one that counts.
And when you say drop the compression, I hope you mean by a built motor, not some shitty thick head gasket. I don't even want to get into the whole thick HG issue.

 

nice cut and paste from H-T!

I agree though, you want the smallest diameter pipe for the CFM's, or you will make the turbo work harder than it needs to. (having to fill the larger pipes with compressed air)

 

Again sorry for opening an old thread, but I am having troubles understanding this... I'm no mechanical engineer and I'm trying to get a grasp on this.. I already have a gt3076r .82 AR and i'm swapping it onto my greddy kit which has mostly 2" piping... I read that it can do 585 cfm max.... But I honestly don't really know what this means... I looked up some charts from garret on the turbo but still could not figure it out.... I guess what I'm trying to ask is what is the most boost I can throw through 2" piping... AND if I should just upgrade to 2.5"... thanks guys.. I was hoping to go around 16 psi on stock HG or 20 psi plus on ILP 3mm.. any help would be appreciated...

 

anyone??

 

you need to read a compressor map and work out where you'll land on it. If you're going to be running the greddy manifold (or are you running a different manifold?), i can't see you hitting the 'max' of the 2.25 piping before you run out steam from other parts of the setup.