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Intercooler piping 3in or 2.5in


Well-known member
Oct 16, 2003
Tacoma, WA
I had to move my windshield washer reservoir in order to run 3" pipes, though i'm actually considering eliminating it, not sure i will want to cut out the nozzles in a cf hood. /ubbthreads/images/graemlins/uhh.gif

Honestly, I don't really see the reason to go 3" unless you have a really big turbo, the only reason I have it is the deal i walked into. Frankly, 3" isn't really necessary for my setup and it should be 75lb/min~ish

if you've got anything smaller, I think the downsides outweigh the upsides.


Well-known member
Dec 5, 2002
Lake Orion, MI
Quoting curtis:
as long as the flow is laminar and the flow doesn't go turbulent benefits can be made but fast transition couplers should never be used. The atoms on the side of your IC pipe are locked on there because of the friction facto/roughness of the pipe then the air molecules pass over each other in sheer into a cone shape point.

Whether laminar or turbulent, I agree with the transitions you're talking about. However, somewhere in these archives I calculated and posted the Re (reynolds number) for a number of different scenarios and different pipe diameters (actually for intake airflow to dispell the whole "tornado" voodoo gassaver), and just in the Re for air through the pipe alone the airflow goes turbulent at a low rpm, before a lot of turbos begin to boost. However, coming out of the compressor ALL the air will be turbulent, anyway, so calculating the Re for the flow through the pipe is really not necessary. Even if it was, going into and through the IC would quickly change that. /ubbthreads/images/graemlins/smile.gif Which is actually beneficial for cooling b/c as you stated laminar flow has boundary layers which are much greater than turbulent flow, anyway.

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