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Old 03-24-2003, 10:58 PM   #1
Scooby Newbie
Member#: 8387
Join Date: Jul 2001
Chapter/Region: SCIC
Location: chino/fullerton
99 GM8 EJ20g
86F blue steel mica

Default is it ok to have a 3" up and down pipe? and go 3 all the way back?

is it ok?
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Old 03-24-2003, 11:00 PM   #2
Scooby Specialist
Member#: 7453
Join Date: Jun 2001
Chapter/Region: BAIC
Location: Bay Area, CA
2014 Scion FR-S
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I wouldn't think that a 3" up-pipe would be good as its going to be a lot larger than the manifold outlet and the turbo inlet which won't be good for flow. 3" all the way on the post turbo side is good though.
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Old 03-25-2003, 09:00 AM   #3
Scooby Newbie
Member#: 21487
Join Date: Jul 2002
Location: Winter Park Florida
Thumbs down 3" Upipe Bad

A 3" uppipe is not good. The manifold outlet diameter is about 2". So you are basically "dumping" the exhaust into a larger volume pipe which would cause too much turbulence as it gets to the turbo. You want the upipe to match the manifold outlet and turbo inlet as close as possible. Some uppipes are 2-1/4" diameter or less at the manifold and go down to 2" at the turbo which acts as a velocity chamber causing the exhaust gases to compress letting the turbo spool faster etc. I am not a physics expert and I am sure someone else out there can explain in more detail but you getthe jist of it.
so you basically need to stay away from 3" uppipes if there are any outl there.
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