What are stock heads flowing?
John, get ahold of Jason @ TR. He's flowed all the years and has the answer to your question. You might be able to do a search and find it, I have seen him post the #'s before..
Josh
Josh
TECH Addict
Joined: Dec 2001
Posts: 2,298
Likes: 2
From: new england
Originally Posted by Pro Stock John
Anyone have stock head flow numbers for 5.7's, 5.3's, 6.0's and LS6's?
In a nutshell John they all flow around 235 cfm in the .500" lift range, LS6 and 6.0 slightly higher. Exhaust is around 170cfm at same lift on all. This I/E ratio is why LS1 seems to like single pattern cams or even higher intake to exhaust splits.
On The Tree
Joined: Jun 2002
Posts: 116
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From: new york
6.0's and ls6 heads dont flow anything alike. Im looking for the flows I have on stock heads all I have are intake flows on 862, 241,806,and ls6 heads through an ls6 intake. I will look for the other flow sheets when I get back to work tommorow
-------241--ls6---806--862{5.3l
200 - 134 -135 - 127 - 128
300 - 185 -186 - 179 - 176
400 - 216 -220 - 212 - 204
450 - 222 -233 - 214 - 213
500 - 226 -238 - 220 - 216
550 - 228 -238 - 220 - 210
600 - 228 -236 - 221 - 210
-------241--ls6---806--862{5.3l
200 - 134 -135 - 127 - 128
300 - 185 -186 - 179 - 176
400 - 216 -220 - 212 - 204
450 - 222 -233 - 214 - 213
500 - 226 -238 - 220 - 216
550 - 228 -238 - 220 - 210
600 - 228 -236 - 221 - 210
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On The Tree
Joined: Oct 2002
Posts: 111
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From: Hubert, North Carolina
I was looking at the numbers that were posted on Jason's flow sheets. 6.0's seem to flow considerably less than the LS6 casting. 6.0 heads are being advertised as having the same flow and port design as the LS6's minus the larger combustion chamber on the 6.0's. If this is true and all conditions being relatively similar on the flow bench how could these numbers be so different? 
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Originally Posted by absolute
6.0's and ls6 heads dont flow anything alike. Im looking for the flows I have on stock heads all I have are intake flows on 862, 241,806,and ls6 heads through an ls6 intake. I will look for the other flow sheets when I get back to work tommorow
-------241--ls6---806--862{5.3l
200 - 134 -135 - 127 - 128
300 - 185 -186 - 179 - 176
400 - 216 -220 - 212 - 204
450 - 222 -233 - 214 - 213
500 - 226 -238 - 220 - 216
550 - 228 -238 - 220 - 210
600 - 228 -236 - 221 - 210
-------241--ls6---806--862{5.3l
200 - 134 -135 - 127 - 128
300 - 185 -186 - 179 - 176
400 - 216 -220 - 212 - 204
450 - 222 -233 - 214 - 213
500 - 226 -238 - 220 - 216
550 - 228 -238 - 220 - 210
600 - 228 -236 - 221 - 210
The 5.3 head with a smaller valve is about the same...
Is it because of the 97-98 intake valve that doesn't have a 'back-cut'
to it ...
Dave
The LS6 head on Jason's pictures says it was flowed with a "Radiused Inlet" on the intake port. None of the other heads have that inlet. Would this skew the LS6 numbers some compared to the other 3 heads?
TECH Enthusiast
Joined: Dec 2001
Posts: 563
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From: Macomb, MI
Hot Rod 2/04 has flows listed for Stock LS1, Stock LS6, GM PP LS6, and AFR Ported Heads. I can't remember the #'s, I'll post them tomorrow if nobody beats me to it. They are in the AFR article.
The numbers you want to look at are the ones attached to a stock ls6 intake. A head can flow really well, but when put through the intake fall on it's face.
Yes, the LS6 heads could see 20+ cfm more without an intake, but that does nothing to compare it to real world values. You must flow all heads through the same intake to have a comparison. Due to the nature of the ports, a lot of turbulence occurs when air enters the heads from the intake. When you look at a LS6 head that may flow 260cfm through a radiused inlet vs. a LS1 head that flows 230cfm through a radiused inlet -- this means nothing. In the real world you are not flowing air through a radiused inlet, but you are flowing it through an intake manifold.
Jay and I did the testing one day I was at his shop and I can confirm the following numbers
------241--ls6---806--862{5.3l
200 - 134 -135 - 127 - 128
300 - 185 -186 - 179 - 176
400 - 216 -220 - 212 - 204
450 - 222 -233 - 214 - 213
500 - 226 -238 - 220 - 216
550 - 228 -238 - 220 - 210
600 - 228 -236 - 221 - 210
Through the same exact LS6 Intake Manifold
Bottom Line: Throw away the flow #'s through the radiused inlet because in the real world you'll never have that condition.
Yes, the LS6 heads could see 20+ cfm more without an intake, but that does nothing to compare it to real world values. You must flow all heads through the same intake to have a comparison. Due to the nature of the ports, a lot of turbulence occurs when air enters the heads from the intake. When you look at a LS6 head that may flow 260cfm through a radiused inlet vs. a LS1 head that flows 230cfm through a radiused inlet -- this means nothing. In the real world you are not flowing air through a radiused inlet, but you are flowing it through an intake manifold.
Jay and I did the testing one day I was at his shop and I can confirm the following numbers
------241--ls6---806--862{5.3l
200 - 134 -135 - 127 - 128
300 - 185 -186 - 179 - 176
400 - 216 -220 - 212 - 204
450 - 222 -233 - 214 - 213
500 - 226 -238 - 220 - 216
550 - 228 -238 - 220 - 210
600 - 228 -236 - 221 - 210
Through the same exact LS6 Intake Manifold
Bottom Line: Throw away the flow #'s through the radiused inlet because in the real world you'll never have that condition.
Launching!
Joined: Mar 2003
Posts: 250
Likes: 0
From: Oceanside CA
Originally Posted by LS1derfull
In a nutshell John they all flow around 235 cfm in the .500" lift range, LS6 and 6.0 slightly higher. Exhaust is around 170cfm at same lift on all. This I/E ratio is why LS1 seems to like single pattern cams or even higher intake to exhaust splits.
