exhaust/header question
Thread Starter
Joined: Mar 2004
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From: brockville, ont, canada
exhaust/header question
i'm currently looking at a stainless cat-back for my gsr.
i've got enough cash to also grab a header and am aiming for the jdm itr one peice. problem is, my exhaust is going to be 2.25in and the collector on the header is 2.5in.
i'm going to stay pretty basic untill the end of summer, so why shouldnt i just buy a 2.5in exhaust?
i know basic bolt on exhaust size should be 2.25in, but if the jdm itr header has a 2.5in collector does that mean the jdm itr had a 2.5in exhaust?
i'm just looking for maximum usible flow without hurting performance
i've got enough cash to also grab a header and am aiming for the jdm itr one peice. problem is, my exhaust is going to be 2.25in and the collector on the header is 2.5in.
i'm going to stay pretty basic untill the end of summer, so why shouldnt i just buy a 2.5in exhaust?
i know basic bolt on exhaust size should be 2.25in, but if the jdm itr header has a 2.5in collector does that mean the jdm itr had a 2.5in exhaust?
i'm just looking for maximum usible flow without hurting performance
Member
Joined: Aug 2002
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From: NorCaL/SoCaL
It wont be too bad. I'm running the jdm header to itr exhaust (2.36" I think). I don't want to upgrade the exhaust since it'll draw attention and I like the sound of the backpressure on/off the throttle.
Thread Starter
Joined: Mar 2004
Posts: 455
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From: brockville, ont, canada
ok so... stupid question...
i'm going to have a test pipe made to go from 2.5in to 2.25in
will that help to create better flow between the two sizes? i dont think theres a cat on the market that will fit both sizes
i'm going to have a test pipe made to go from 2.5in to 2.25in
will that help to create better flow between the two sizes? i dont think theres a cat on the market that will fit both sizes
Darth ModerVader
Joined: Jan 2001
Posts: 11,539
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From: Mustafar
Re: exhaust/header question (tngay)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tngay »</TD></TR><TR><TD CLASS="quote">that 2.5inch will hurt ur perforence believe it or not. that is just to big.</TD></TR></TABLE>
Can you provide specific empirical evidence of this (i.e., a dyno sheet)? In tests performed a few years ago by a somewhat prominent H-T member, even a 3 inch exhaust didn't result in the power loss you're suggesting. Granted, the tests were done on an ITR, but the B18C1 and B18C5 are similar enough that the testing should remain reasonably valid for both engines, especially when the discussion is regarding a 2.5" system. If I were running a header with a 2.5" collector, I would definitely run both at 2.5" cat and a full 2.5" exhaust system (or at the very least, a 60 mm system).
Also, just as an additional piece of information regarding the post by daLixz25, the majority of the OEM ITR exhaust is 2.25" diameter (with various smaller diameter areas).
Can you provide specific empirical evidence of this (i.e., a dyno sheet)? In tests performed a few years ago by a somewhat prominent H-T member, even a 3 inch exhaust didn't result in the power loss you're suggesting. Granted, the tests were done on an ITR, but the B18C1 and B18C5 are similar enough that the testing should remain reasonably valid for both engines, especially when the discussion is regarding a 2.5" system. If I were running a header with a 2.5" collector, I would definitely run both at 2.5" cat and a full 2.5" exhaust system (or at the very least, a 60 mm system).
Also, just as an additional piece of information regarding the post by daLixz25, the majority of the OEM ITR exhaust is 2.25" diameter (with various smaller diameter areas).
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