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Old 11-04-2020, 11:11 AM   #1
Jussi Alanko
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Join Date: Jun 2020
Location: Finland
Default Optimum intercooler piping size?

What is optimum size for 4-500hv redblock?
I know that at least 800hp is taken out with 2.5" ic pipings.
But i put a 70mm tb to intake, and it's outer diameter is exactly 3", But holset hx40 super's compressor diam. is 60mm, also i'm looking for do88 intercooler, which is designed in stockholm and they have taken measurements of this intercooler too:

This ic has also a 60mm pipings.

So i I thought 60mm is enough, but is it?

who can calculate airspeed in 60mm pipe at 2.1liter engine at 7200rpm (limiter).
If airspeed exceeds 0.4mach flow resistance will go up very quickly. I think that optimum will be something about 0.3mach. I have read this somewhere, but i can't remember now where!

Flow must be laminar in every cases, if pipe is too small flow goes turbulent, and if pipe is too big then also flow go to laminar to turbulent.

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Old 11-04-2020, 07:14 PM   #2
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Join Date: May 2017
Location: Eldorado Springs Mo.

This has been discussed before. I believe it was said that 2.5 is more than enough. Im setting mine up with 3 inch intercooler piping. Search in google, I believe you will find the info your looking for.
90 Volvo 240-my current setup.
B230ft rebuilt -8.8 comp. -Stage 3 rsi cam
3 inch ex.-GTX3076r turbo ballbearing.
ebay intercooler-3 inch IC piping- Oil cooler with 10an hose.
port stock intake (weak, having a custom intake by viking fab.)
Megasquirt 2-1300cc injectors (running E85)
530 head with big valves ported and assemble by culberro

sons car- 93 240-15g turbo-chipped-95,000 miles. Slick car

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Old 11-04-2020, 07:19 PM   #3
Harlard's Avatar
Join Date: May 2007
Location: PDX

Use the pipe diameter that makes the most sense in terms of size changes and transitions. Don't overthink it.

Herr Harlard am Erstens

1979 242 DL

Originally Posted by t8fanning View Post
My knob has a big chunk of steel on it
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Old 11-04-2020, 07:42 PM   #4
Jussi Alanko
Board Member
Join Date: Jun 2020
Location: Finland

You are righ't i'm clearly overthinking this thing, but i wan't all areas of this engine build to be optimum.
Now, i'm thinking that i use 60mm tubing, it's 2.36", i find this chart at internet.

if i have calculated airflow right my engine uses about 550cfm air at 2.5pressure ratio, and if this chart was right it means that in max speed and pressure airspeed in intercooler piping is something about 0.24mach, which is very good airspeed, flow stays laminar and doesn't exceed 0.4mach limit, after that limit flow restriction growhts rapidly.
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