DIY Turbo Discussion greddy on a 1.8? homebrew kit?
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Intercooler Pipe sizing

Old 03-26-2008, 06:49 PM
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Default Intercooler Pipe sizing

Purchased my intercooler yesterday. 2.5" in/out and the greddy turbo is 2" out. I was hoping to keep as much of the piping as small as possible (same as turbo outlet) to keep throttle response optimal. I could do all 2" piping, with reducers on each end of the intercooler and at the throttle body, or should I just do 2" turbo -> IC, @" to 2.5" adapter onto the IC and then 2.5" IC -> TB ?
Coky wrote about the exhaust that optimally it should never decrease in radius - optimally it should slowly increase in radius the farther downstream it goes, and I would assume that would be the case for the intake tubing, so should I not reduce it back to 2" once it goes to 2.5" at the IC?

Your thoughts are appreciated.
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Old 03-26-2008, 08:13 PM
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I think the idea of the exhaust is to keep it lower pressure downstream and therefore inducing flow to the low pressure from the high at the turbo.

As for intercooler piping, I believe you are trying to pressureize as much of the system as you can as quickly as you can. Smaller piping will fill quicker but will also have a larger pressure drop across it due to the larger contact area per volume of air. However this pressure drop may not be very large at all. I believe Corky suggests that the length and diameter of the piping, to an extent does not have a huge effect on throttle response and pressure drop as opposed to the number of bends which will have more effect.

Please feel free to offer any corrections.

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Old 03-26-2008, 09:18 PM
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is all the whatever you feel comfortable with and you'll see no real gain/loss either way.
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Old 03-26-2008, 10:50 PM
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flow and pressure are two different things
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