Typical flow numbers for Stage 1 heads?
04-09-2004, 05:46 PM
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Typical flow numbers for Stage 1 heads? Hi guys, I'm in the process of putting a motor together. Right now I have some 241 casting 5.7 heads, 02 LS6 cam, LS6 intake, etc. I'm going to get a Stage 1 port job to a .550" lift for the LS6 cam and get them milled .030 for some extra compression. I've been out of the "stage 1" loop so long I'm wondering what some typical/good flow numbers (intake and exhaust) with stock valves are. TIA ~tony 
04-12-2004, 12:48 PM
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There are too many "depends" in your question. 
I'd expect 270 - 275cfm @ .550" lift out of a "stage I" port. .550" is right at the plateau. Most LS1 heads flatten out at .550" and become too turbulent unless the porter really knows what he is doing. I've flowed a lot of "Stage II and III" heads with the same issue, so it is not uncommon.
I'd expect 270 - 275cfm @ .550" lift out of a "stage I" port. .550" is right at the plateau. Most LS1 heads flatten out at .550" and become too turbulent unless the porter really knows what he is doing. I've flowed a lot of "Stage II and III" heads with the same issue, so it is not uncommon.
04-12-2004, 02:08 PM
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Thanks for the info! Yeah .550 or .560 being the plateau, I'm on a budget so I don't want to go with bigger vavles I was thinking around 270-280cfm, I there are some stage I ports getting 290 cfm at a .550 lift but they have bigger vavles. Any more opinions are welcome!
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04-12-2004, 02:38 PM
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I captured this some time ago on ls1tech:
Intake
.100 - 67
.200 - 142
.300 - 210
.400 - 254
.500 - 290
.550 - 304
.600 - 286
Exhaust
.100 - 50
.200 - 104
.300 - 150
.400 - 185
.500 - 203
.550 - 210
.600 - 212
That is supposed to be for the LS6 CNC heads
http://www.sdpc2000.com/cart.asp?act...979&pid=154062
http://www.sdpc2000.com/cart.asp?act...=1979&pid=8174
Note one part number is milled .055 for a 60cc CC.
Intake
.100 - 67
.200 - 142
.300 - 210
.400 - 254
.500 - 290
.550 - 304
.600 - 286
Exhaust
.100 - 50
.200 - 104
.300 - 150
.400 - 185
.500 - 203
.550 - 210
.600 - 212
That is supposed to be for the LS6 CNC heads
http://www.sdpc2000.com/cart.asp?act...979&pid=154062
http://www.sdpc2000.com/cart.asp?act...=1979&pid=8174
Note one part number is milled .055 for a 60cc CC.
Last edited by Zeta; 04-12-2004 at 02:40 PM. Reason: clarity
04-12-2004, 04:03 PM
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Thanks for link, although I know that LS6 heads in their bare casting out perform the 5.7 241 casting by quite a bit, it's a good comparison.
