1 7/8 header worth it for l92 heads?

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Mar 21, 2007 | 10:34 PM

formula17

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From: Macomb, Michigan

1 7/8 header worth it for l92 heads?

Anyone run a back to back CHASSIS dyno or engine dyno? Saw a post on here that had one on an engine then the other on a chassis dyno. Just wondering what everyone thinks.

Thanks,
Nick

Mar 21, 2007 | 10:45 PM

NoGamesLS1

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I remember seeing a post of someone going 1 3/4 to 1 7/8 and gained something like 25 rwhp

Mar 21, 2007 | 10:54 PM

osuqsz06

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From: nc

i went with american racing 1 7/8 w/ ls7 d port flanges and big collectors for my l92's

Mar 25, 2007 | 05:07 PM

03 BUSA

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From: Kannapolis, NC

I would say it depends on the CI not the heads. Since the bore min is over 4.0 I would say 1 7/8. IMO

Mar 25, 2007 | 06:44 PM

rons 00z

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according to QTP they gained no power going from 1 7/8 to 1 3/8 on a 402. i'm curious on where it's time to change to the bigger header.

Mar 25, 2007 | 06:59 PM

Pwebbz28

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From: Denton, Tx

I wouldnt think you would gain anything if the exhaust port opening is still smaller than or equal to 1 3/4. After you get a bigger port you would most definately need 1 7/8.

Mar 25, 2007 | 07:41 PM

PowerShift408

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From: Bowling Green, KY

Quote:

Originally Posted by Pwebbz28

I wouldnt think you would gain anything if the exhaust port opening is still smaller than or equal to 1 3/4. After you get a bigger port you would most definately need 1 7/8.

I can't really think of any head on the market that has even a 1.75'' exhaust port. Usually 1.6'' or smaller.

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Mar 25, 2007 | 09:12 PM

Phynix

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From: Santa Ana

It really depends, I'm running the 1 7/8s stepped to 2in with a 3.5in collector and I gained some powereven after I added the cats to get some back presure from the 1 7/8s. I'm at stock cubes, and I could feel the difference when I went to the 1 7/8s from the 1 3/4s. and the dyno verified that, I think in has more to do with how aggressive your setup is aka how much air you are flowing