At what horsepower level does a single 3" exhaust start to become a restriction?
#1
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At what horsepower level does a single 3" exhaust start to become a restriction?
I'm doing an LS swap in my IROC. 402, LS3 heads, blah blah blah. I expect to be in the range of 500-520 RWHP. I currently have a 3" single over-axle exhaust going through a 3" muffler with a single driver side tail pipe. I'd planned on going to a bigger exhaust when I do the LS swap, but if what I have won't be a restriction, then I'd rather just keep what I've got.
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#3
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IIRC you need roughly 2.2 cfm of exhaust flow per hp to flow unrestricted. That said its not like 3" will rob 50hp away on a 500whp build vs a single 4". The difference would be noticeable but not huge. The sticky in the external engine section has some great info but sadly a LOT of the great pics and charts that jrp originally posted are now gonzo or dead links. Heres a pretty good guesstimate for a quick read
https://ls1tech.com/forums/2987587-post19.html
https://ls1tech.com/forums/2987587-post19.html