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ls9 vs ls7 vs ls3 heads on a ls3

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Old Nov 12, 2010 | 06:39 PM
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Default ls9 vs ls7 vs ls3 heads on a ls3

I was wondering if anyone has experience putting ls7 or ls9 heads on a ls3 block. How do they compare to a ls3 heads? Hp gains? Flow numbers? Any major modifications needed? I know the ls3 can be bored out to 4.100 so the ls7 can fit even though its not idea.
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Old Nov 14, 2010 | 10:40 PM
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Ls3 and ls9 are very similar. Ls9 has a blend bump In the intake chamber to help mix fuel at low rpm on forced induction better. So not much gains there... Ls7 would be great, but you have to check it engine by engine, clearance is very close... I've heard of it being done...
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Old Nov 15, 2010 | 01:49 PM
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I always thought the LS7 heads needed a min. 4.125 bore. Not really positive though.
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Old Dec 10, 2010 | 07:36 PM
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ARENT the ls9 heads lower comp
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Old Dec 16, 2010 | 09:41 PM
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bump....
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Old Dec 16, 2010 | 10:01 PM
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believe you need a 4.1 bore min for ls7 heads, tsp is making ls7 heads for 4.065 bore soon.
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Old Dec 30, 2010 | 03:54 AM
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LS9 heads use a larger head bolt 12mm vs 11mm on all the rest would that not limit the LS9 heads to only LS9 blocks OR you will have to have the LS3 block machined for the 12mm studs....correct or am I missing something here?
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Old Jan 10, 2011 | 05:19 AM
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Originally Posted by 68 SS
LS9 heads use a larger head bolt 12mm vs 11mm on all the rest would that not limit the LS9 heads to only LS9 blocks OR you will have to have the LS3 block machined for the 12mm studs....correct or am I missing something here?
Can Some one help clarify if this will prevent swapping LS9 Heads on lets say a 6.0 or something, Thank you
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Old Jan 10, 2011 | 10:12 AM
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I'd like to know as well about ls9 heads on an ls3 block. Could stepped bolts or studs be used? I have heard of iron blocks using 1/2" bolts or studs but not aluminum. The LS9 heads are a great price considering the Ti valves.
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Old Jan 10, 2011 | 10:17 AM
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I was told by See5 I believe is his screen name that a few people are using the heads with the 11mm studs. I know they are dowel located but still I would not run them that way. I bought a set of LSA heads that are on their way to WCCH for porting we will see what they can handle, I hope they will be strong enough to take the F1R...
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Old Sep 26, 2014 | 04:38 PM
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Lingenfelter makes LS9 heads for the ls2,ls3, and ls9, all you gotta do is run ARP head studs because of the thicker clamp stuff, and you need valve lash caps for the titanium valves. 69.5CC chamber and such.

http://www.lingenfelter.com/mm5/merc...9#.VCXaDhadog8
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