formula17

iTrader: (4)

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

NoGamesLS1

iTrader: (16)

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

osuqsz06

iTrader: (2)

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

03 BUSA

iTrader: (25)

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

rons 00z

iTrader: (10)

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.

Pwebbz28

iTrader: (31)

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.

PowerShift408

iTrader: (44)

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

Phynix

iTrader: (3)

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