Stock LS1, Put 5.3 Heads On? Which Casting?
02-10-2008, 10:44 AM
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Stock LS1, Put 5.3 Heads On? Which Casting? Hey, I have a number of questions. Hope I get get each one answered. 
I have a stock 1999 LS1. I hear it would raise the compression -- and thus the performance -- to put stock 5.3 heads on it.
I don't know anything about it, but is that true?
I looked through the parts for sale thread and saw a couple different castings. Mainly, 317, 706, 862. Does it matter which ones? Which ones do i most want for my '99? Seems like the 317 are what people want...
If I go this route, I'm thinking of doing a 224/224 cam at the same time. Would that be ok? Should I use the stock LS1 head gasket and everything? I mean, will they bolt right down no big deal?
These heads came of an "LQ4", right?
I have a stock 1999 LS1. I hear it would raise the compression -- and thus the performance -- to put stock 5.3 heads on it.
I don't know anything about it, but is that true?
I looked through the parts for sale thread and saw a couple different castings. Mainly, 317, 706, 862. Does it matter which ones? Which ones do i most want for my '99? Seems like the 317 are what people want...
If I go this route, I'm thinking of doing a 224/224 cam at the same time. Would that be ok? Should I use the stock LS1 head gasket and everything? I mean, will they bolt right down no big deal?
These heads came of an "LQ4", right?
02-10-2008, 11:00 AM
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706 are from a 99+ 5.3. 852 are from a 99+ 4.8. 317 are from a 01+ 6.0. The 5.3 and 4.8 heads a 1.89" intake valve size which is smaller than the 2.00" valves on your LS1 heads. The 4.8 or 5.3 heads will bump up your compression, but you would need some head work to fit larger valves to get the flow numbers back up.
02-10-2008, 11:08 AM
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The benefit of the truck head castings is the smaller combustion chamber that allows for higher compression and better PTV clearance than you would get with milled LS1 heads. But yes, you would need some head work to see the most gains out of these castings. Many of our sponsors sell reasonably priced ported truck heads that will work quite nicely for you.
02-10-2008, 11:24 AM
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The most gains, i understand. Are you saying there are little to no gains going to a stock 5.3 head from a stock 241 head? If there are gains, are you saying i want the 706 heads and not the 317 heads?
Anyway, i would love to get ported heads, but i can't for anywhere near $100 + shiping!
Anyway, i would love to get ported heads, but i can't for anywhere near $100 + shiping!
02-10-2008, 12:08 PM
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I haven't seen any dyno numbers for a stock 5.3 head swap on an LS1. But, with the smaller valve size, I am quite certain that there would be little to no gains at all (maybe even a loss).
The 317 heads have a larger combustion chamber than LS1 heads, but with the same valve size. In this case you would probably have the same flow numbers, but lower compression and less power.
Basically, if you want to use truck heads you need some work done to them to see any gains. If you only want higher compression, just mill your stock heads.
The 317 heads have a larger combustion chamber than LS1 heads, but with the same valve size. In this case you would probably have the same flow numbers, but lower compression and less power.
Basically, if you want to use truck heads you need some work done to them to see any gains. If you only want higher compression, just mill your stock heads.
