So with more and more big cube LS motors out there just wondering what kind of results people have been getting going to larger headers. And issues that you might have had such as spark plug clearance? I currently have Kooks 13/4 to 17/8 stepped. Any idea what I might gain by going to a 17/8 or 2" header? Any decrease in torque going to larger diameter?

 

I don't think you'd see a loss of tq or hp. I also don't think you'd start to see an increase in tq/hp until the middle - top 1/3rd of the power band. Probably at least 10rwhp or more by stepping up to 2" primarys.

 

I'm definitely going 1 7/8 stepped to 2"....for my new 441ci.

It depends on your top end.......are you going to have a top end thats going to allow your 440ci to be a 440ci???? If your top end is the weak link and can't properly feed a 440ci, then you'll end up with something less...like maybe a 408ci or a 416ci.......

If you have a real good top end that can feed that many cubes........you really need to go with the 1 7/8 stepped to 2". If your top end is so-so......then 1 3/4 stepped to 1 7/8 or just 1 7/8 will be fine.

I'm going either Tony Mamo AFR 245's or ported LS7's.......so I'm gonna be feeding my 441ci nicely.......so bigger the better for LT's for mine.

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If you're gonna step it...go all the way imo. Full 2" here, but the 460 needs to breath.....

 

Just wondering if anyone had before and after numbers?

 

I am also doing a 440 (solid roller) since the 408 threw a rod a couple weeks back. I have Kooks stepped 1 7/8 and thought about going larger yet. Heads are still up in the air. Those 305cc LS7 heads from Mast seem like a great option. I'm considering biting the bullet and going for a set of All Pros as well.

 

I changed out my Kooks 1 7/8's for a stepped 1 7/8 to 2" on my 445. It really shines up top but down low is about the same. Like stated above, if you have all the right top end for it to breath you can't more then benefit from it. I would at least run a 1 7/8 IMO