5.3l or ls6 heads?
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I would imagine you would actually see an increse, thats if you just change heads not if you throw a giant cam and a heavy foot in the mix, but just swapping heads will gain mileage because the heads will bump compression and efficiency, heads are win win.
Oh and the 5.3 truck heads have small chambers so you dont have to mill the **** out of them to get higher compression, that I can tell thats the only real benefit to them, and one other thing I have been wondering is if the 5.3's have quench pads, if not then the LS6's would get my vote.
Last edited by 00pooterSS; Sep 23, 2008 at 10:14 AM.
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Largest Stocking Distributor of LS-x Engines / CHECK OUT OUR NEW WEBSITE!
COMP - FAST - PACESETTER - DIAMOND RACING - EAGLE SPECIALTY PRODUCTS - CALLIES - COMETIC GASKETS
RAM CLUTCHES - MOSER ENGINEERING - KOOK'S HEADERS - ARP - GM BOLTS AND GASKETS - MSD - NGK
POWERBOND - ASP - AND MORE!
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Alot of what is done to the aftermarket 5.3's is port and chamber work that increase flow and efficiency, as Matt said it wont be an "appreciable" gain but you would have a gain in compression from going from 66.67 cc chambers to 61.5 ( believe those numbers are correct, correct me if I am wrong ) I would venture to say slapping them on the compression gain would be around 15-20 but worked over your looking at closer to 40+ depending on supporting mods. Also I do not know what the heads flow stock for stock, there could even be a drop in power if the 5.3's ports are lesser than the stock as far as flow.
Matt could you chime in on if the 5.3's have quench pads like the LS6's do please.






