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Old Jul 21, 2011 | 09:27 PM
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i was told to post this here for more info so here it goes


looking for a good cam for ported l92 heads on an lq4 block going in a six speed full weight stock gear street car?

every dealer i ask has a completly different setup some say big big split in duration some say 4 or 5 and even some in the 220s
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Old Jul 22, 2011 | 09:02 AM
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Here's some general info that you might find helpful.

An L92/LS3 head has intake ports with superior flow over a stock LS6/LS2 cathedral port. 1. You can get by with about 4-6 degrees less duration on the intake and make the same power as a correctly spec'd cam with cathedral port heads.
2. The L92/LS3 exhaust flows the same or slightly better than LS6/LS2 heads. There is no need to make the exhaust flow numbers greater than what you'd normally use for an LS6/LS2 head.
3. A lower compression (9.6:1 with L92 heads) LQ4 will need another degree or two of overlap compared to a higher compression engine of the same displacement. Lower compression responds to narrower LSA.
4. A 364 will want about 3 more degrees of overlap/duration to behave like a 346 LS1.

So let's say that you find an LS6 with the street manners and power that you'd like to emulate and in this example it has a 228/230 112LSA cam. Using the illustration above you would:
1. Subtract 4-6 degrees of intake duration. We'll split the difference and call it 5. Now we're at 223 for intake.
2. Keep the exhaust duration at 230 since our flow is comparable.
3. Reduce our LSA to 111 to account for the lower static compression (9.6:1 vs 10.5:1).
4. Increase our duration by 3 on both intake and exhaust to account for the extra 18 cubic inches of the 364 vs the 346. Now we're at 226/233 111LSA.

So basically, we'd have a cam for a low compression 364 with L92 heads that would perform and behave like LS6/LS2 heads on a higher compression 346.
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Old Jul 22, 2011 | 03:31 PM
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Originally Posted by Patrick G
Here's some general info that you might find helpful.

An L92/LS3 head has intake ports with superior flow over a stock LS6/LS2 cathedral port. 1. You can get by with about 4-6 degrees less duration on the intake and make the same power as a correctly spec'd cam with cathedral port heads.
2. The L92/LS3 exhaust flows the same or slightly better than LS6/LS2 heads. There is no need to make the exhaust flow numbers greater than what you'd normally use for an LS6/LS2 head.
3. A lower compression (9.6:1 with L92 heads) LQ4 will need another degree or two of overlap compared to a higher compression engine of the same displacement. Lower compression responds to narrower LSA.
4. A 364 will want about 3 more degrees of overlap/duration to behave like a 346 LS1.

So let's say that you find an LS6 with the street manners and power that you'd like to emulate and in this example it has a 228/230 112LSA cam. Using the illustration above you would:
1. Subtract 4-6 degrees of intake duration. We'll split the difference and call it 5. Now we're at 223 for intake.
2. Keep the exhaust duration at 230 since our flow is comparable.
3. Reduce our LSA to 111 to account for the lower static compression (9.6:1 vs 10.5:1).
4. Increase our duration by 3 on both intake and exhaust to account for the extra 18 cubic inches of the 364 vs the 346. Now we're at 226/233 111LSA.

So basically, we'd have a cam for a low compression 364 with L92 heads that would perform and behave like LS6/LS2 heads on a higher compression 346.
Great info.
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Old Jul 23, 2011 | 06:01 PM
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Patrick,
Based on your formula above, an L92/L76 owner can achieve the same HP level as a LS1 owner, is that right?? With more cubes and better heads, the power level would be the same but with less lope and be more stealthy to the untrained ear?? Am I understanding this correctly??

Last edited by DV327; Jul 23, 2011 at 09:21 PM.
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Old Jul 23, 2011 | 06:15 PM
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so comp wants me to run a 231-247 dur with a .612-.624 lift on a 113 lsa
? is is that possible concerning piston to valve clearence texas speed says nothing bigger then a 236 on durration
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Old Jul 23, 2011 | 06:18 PM
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i orginally had an ms3 (237-242 .603-.609 112) so pat if i do the math right and the way u said it if i wanted the same type of cam in the 6.0 i would need a 234-245 .603-.609 on a 111 lsa?
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Old Jul 23, 2011 | 06:59 PM
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Originally Posted by 98_SS
so comp wants me to run a 231-247 dur with a .612-.624 lift on a 113 lsa
? is is that possible concerning piston to valve clearence texas speed says nothing bigger then a 236 on durration
That's sounds about right. Patrick G specd the cam for my 416ci LS3 with ported L92 heads. My compression is 11.32:1. I'm running a 239/247 .624/.624 114+2 , and it has great street manners.
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Old Jul 24, 2011 | 08:43 AM
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OP here is a link that may help you understand splits a little better.

http://forums.corvetteforum.com/c6-t...spinspeak.html

I've been searching & trying to understand the valve events better as my current configuration is less than desirable. My heads are cathedral so the cam events required are different than your's. As a I mine the cam thing I find a lot of good & bad discussion regarding both cylinder heads.
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