Should I go with my 5.7's or my 5.3's?
01-15-2004 | 08:17 PM
#21
a Ported 5.3's & 5.7's with the same SIZE valves flow similar numbers. I think the 5.7's may have a slight edge. The key is NOT peak flow numbers that's almost meaningless. The mid lift numbers are FAR more important. Likewise, that the heads can flow with the intake in place matters more than what the heads flow without the intake. If your limited to ~290cfm with great heads thru your LS6 intake so what the heads peaked at 320 w/o the intake. A lot of ported 300cfm+ heads will struggle to get 260 cfm thru the intake.
As for welding up a set of 5.7's that can get expensive and if it's not done properly one can really be in for problems. This also tends to be more expensive.
The 6.0 head is also excellent and can out flow either 5.7 or 5.3
Originally Posted by KingCrapBox
You said that the benefit of 5.3's over 5.7's was the compression that you gain from going with 5.3L heads, even though they're easily out-flowed by 5.7L heads.
Why not get a set of 5.7L heads, port them to flow 320ish, and then weld material to the combustion chamber so that you get not only the awesome CFM numbers, but also the added compression from having the 5.7L's milled. Wouldn't that be the best worlds?
That would save somebody from having to decide between having 300+ CFM flow numbers and more compression. They could simply have both.
Why not get a set of 5.7L heads, port them to flow 320ish, and then weld material to the combustion chamber so that you get not only the awesome CFM numbers, but also the added compression from having the 5.7L's milled. Wouldn't that be the best worlds?
That would save somebody from having to decide between having 300+ CFM flow numbers and more compression. They could simply have both.
As for welding up a set of 5.7's that can get expensive and if it's not done properly one can really be in for problems. This also tends to be more expensive.
The 6.0 head is also excellent and can out flow either 5.7 or 5.3
Last edited by 99 Black Bird T/A; 01-15-2004 at 09:07 PM.
01-15-2004 | 09:09 PM
#22
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This is what I thought:
6.0 and LS6 heads the same except for chamber volume
All other LS1 heads: 5.7, 5.3, 4.8: the EXACT same casting with the exception of chamber volume and valve sizes. So, if you put the stock size 5.7 valves in a 5.3, you would have the same flow, but with more compression.
6.0 and LS6 heads the same except for chamber volume
All other LS1 heads: 5.7, 5.3, 4.8: the EXACT same casting with the exception of chamber volume and valve sizes. So, if you put the stock size 5.7 valves in a 5.3, you would have the same flow, but with more compression.
