Head Flow Question
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Head Flow Question
I hope head porters respond to my question. Well what i want to know
on a stock cube LS1 with 241 castings can a head flow too much? I'm asking cause i took a set of ported 6.0 heads for a Procharger setup that i was planning. Well the guy told me the heads flow around 300+cfm and he said the heads flow to0 much which actually causes the air to revert backwards towards the intake or cause the air to stall since the motor doesn't draw all 300cfm since a 346cid motor can only pull in so much on it's own. But once i told him the heads were going on a 383cid with about 12#'s of boost. Then he said the flow wouldn't be an issue. So what's the truth? Would a 346cid LS1 be better off with the heads only ported to around 275cfm with the intake runner untouched on a N/A LS1? This guy builds quick 8 cars and used the Pontiac Big Chief heads and fills in the runners to increase the velocity but to also kill some of the flow. Also i knew a guy that had a 2000 WS6 A4 with ported 853 heads and on the bench they only flowed 255cfm and used a 218/224 Comp cam and ran 11.3 to 11.4's with some weight removed and a 4,000 stall. My old 2002 WS6 A4 have ported 241's and only flowed 260-265 cfm with a Comp 216/220 and Vig3600 stall and had no weight reduction and ran a best of 11.78@116.01 mph N/A. I beat some cars with bigger heads and cam and no one believed that i only had those heads and cam. I plan someday if the economy picks up i'm basically match the setup like my WS6. I'm going with the Comp 218/224 for its A4 friendly nature. But i'm thinking of only having the heads ported to flow about 270 to 280 cfm with a stock intake runner and have the stock valves backcut or just lap them in. Does anyone know if 300cfm would help, hurt, or not make any difference? Sorry for the long post...i'm just thinking how my old 241's dynoed over 400rwhp and 395rwtq in a stalled A4 with stock 3.23 10 bolt. Would i gain any ET with 300cfm over a 275cfm head? Thanks all.
on a stock cube LS1 with 241 castings can a head flow too much? I'm asking cause i took a set of ported 6.0 heads for a Procharger setup that i was planning. Well the guy told me the heads flow around 300+cfm and he said the heads flow to0 much which actually causes the air to revert backwards towards the intake or cause the air to stall since the motor doesn't draw all 300cfm since a 346cid motor can only pull in so much on it's own. But once i told him the heads were going on a 383cid with about 12#'s of boost. Then he said the flow wouldn't be an issue. So what's the truth? Would a 346cid LS1 be better off with the heads only ported to around 275cfm with the intake runner untouched on a N/A LS1? This guy builds quick 8 cars and used the Pontiac Big Chief heads and fills in the runners to increase the velocity but to also kill some of the flow. Also i knew a guy that had a 2000 WS6 A4 with ported 853 heads and on the bench they only flowed 255cfm and used a 218/224 Comp cam and ran 11.3 to 11.4's with some weight removed and a 4,000 stall. My old 2002 WS6 A4 have ported 241's and only flowed 260-265 cfm with a Comp 216/220 and Vig3600 stall and had no weight reduction and ran a best of 11.78@116.01 mph N/A. I beat some cars with bigger heads and cam and no one believed that i only had those heads and cam. I plan someday if the economy picks up i'm basically match the setup like my WS6. I'm going with the Comp 218/224 for its A4 friendly nature. But i'm thinking of only having the heads ported to flow about 270 to 280 cfm with a stock intake runner and have the stock valves backcut or just lap them in. Does anyone know if 300cfm would help, hurt, or not make any difference? Sorry for the long post...i'm just thinking how my old 241's dynoed over 400rwhp and 395rwtq in a stalled A4 with stock 3.23 10 bolt. Would i gain any ET with 300cfm over a 275cfm head? Thanks all.
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Man i know its a trick subject, but look at stage 1 heads from 9 years ago. They only
flowed about 275cfm on average. And the good head porters did that without hogging out the intake runners. And the most popular cam then was the B1 and the 222/222 114lsa Hammer cam. And the A4 cars with a 3200-3600 stall were running atleat 11.7's in heavy cars, and 11.4's or quicker with weight reduction. A lot of guys were in the 11's with the B1 and stock 853 castings and 4.10's. And those heads only flowed about 215cfm tops. So what i'm trying to figure out why cars aren't running much quicker in full weight cars that guys don't want to gut their cars. There's cars running mid 11's with stock 243's and TR224 cams with the normal bolt ons. And the 243's max out between 255 to 260cfm. Yet i see cars with 224 or larger cams running heads like the AFR 205's for example that flow 300cfm. So someone must know of an LS1 only revved to 6,500rpm or even lower, i don't think the piston speed is fast enough to draw in all the flow that the AFR's can flow. My buddy works on LS1 cars and other LS based cars. He told me to see what ET's that guys were running before i bought the heads. After research i knew what he was saying. He has customers that swapped out there ported 241's or unported 243 heads with no other changes other a retune. And those guys were shocked that they didn't lower their ET's
or one other customer only dropped a tenth. They were shifting at 6,500 i believe just like they did with the 243 heads. So i'm trying to find out if a 346cid LS1 can actually lower the ET's with heads that flow more than 260 to 270 cfm? Someone must have swapped from stock 241's or 243's to heads that flow 300+cfm.
flowed about 275cfm on average. And the good head porters did that without hogging out the intake runners. And the most popular cam then was the B1 and the 222/222 114lsa Hammer cam. And the A4 cars with a 3200-3600 stall were running atleat 11.7's in heavy cars, and 11.4's or quicker with weight reduction. A lot of guys were in the 11's with the B1 and stock 853 castings and 4.10's. And those heads only flowed about 215cfm tops. So what i'm trying to figure out why cars aren't running much quicker in full weight cars that guys don't want to gut their cars. There's cars running mid 11's with stock 243's and TR224 cams with the normal bolt ons. And the 243's max out between 255 to 260cfm. Yet i see cars with 224 or larger cams running heads like the AFR 205's for example that flow 300cfm. So someone must know of an LS1 only revved to 6,500rpm or even lower, i don't think the piston speed is fast enough to draw in all the flow that the AFR's can flow. My buddy works on LS1 cars and other LS based cars. He told me to see what ET's that guys were running before i bought the heads. After research i knew what he was saying. He has customers that swapped out there ported 241's or unported 243 heads with no other changes other a retune. And those guys were shocked that they didn't lower their ET's
or one other customer only dropped a tenth. They were shifting at 6,500 i believe just like they did with the 243 heads. So i'm trying to find out if a 346cid LS1 can actually lower the ET's with heads that flow more than 260 to 270 cfm? Someone must have swapped from stock 241's or 243's to heads that flow 300+cfm.
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From: Sublette Kansas
Thats a good point... on how cars used to be so fast with such mild setups... Seems like nowadays its go big or go home, yet they don't run that much faster...
I'm planning on doing a mild setup, 222/224 cam and stock 243 heads..
I'm planning on doing a mild setup, 222/224 cam and stock 243 heads..
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Joined: Sep 2003
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From: Raleigh / Rolesville NC
what do the heads flow at each at each of these valve lifts?
.200
.300
.400
.500
.575
.600
I would rather have a great cam and heads that flow from .200 to. .575 then the best flow at .600
I swapped from 241s to polished not ported .243s
small cam 224/224 581/581 112+4
can out run many cars with larger cams up to about 125, then I am toasted.
but up to redline 3rd gear, I can hold my own
.200
.300
.400
.500
.575
.600
I would rather have a great cam and heads that flow from .200 to. .575 then the best flow at .600
I swapped from 241s to polished not ported .243s
small cam 224/224 581/581 112+4
can out run many cars with larger cams up to about 125, then I am toasted.
but up to redline 3rd gear, I can hold my own
