input on flow # ,
04-10-2005, 09:18 AM
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input on flow # , hey guys,just wanted to get your thoughts on my flow #.the heads are 5.3's w/ 2.02 1.57 valves,63cc chambers and 215cc int.port vol. and 81cc exh.port vol.the low-midlifts on the int.are great but backup a lot after .450lift.i told the porter i was more concerned with the low-midlift # and wanted minimal material removed.the swirl ramp was left intact.
flowed on a 3.9 bore, exh was flowed without a pipe.
int. exh.
.200 148 117
.300 210 151
.400 254 189
.450 269 197
.500 248 202
.550 251 207
.600 257 210
.650 263 212
i didn't expect great peak # but am a little dissapointed that they drop off like they do at .500lift.what would cause this?the valve seat angles?porting?
flowed on a 3.9 bore, exh was flowed without a pipe.
int. exh.
.200 148 117
.300 210 151
.400 254 189
.450 269 197
.500 248 202
.550 251 207
.600 257 210
.650 263 212
i didn't expect great peak # but am a little dissapointed that they drop off like they do at .500lift.what would cause this?the valve seat angles?porting?
Last edited by 66deuce; 04-13-2005 at 03:50 PM.
04-10-2005, 09:34 AM
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Who's valves are you using?
I agree with the flow under the curve being more important. If you take the valve timing event and express it on a time plot you'll see the valve spends very little time at max lift. All your power is made before max lift especially important is flow when the valve just opens and the chamber gets a charge of A/F in. Of course it's all tied together and more complex then I can explain.
All that being said, I'm not sure how your numbers are, I would have expected a little more flow...t I'm doing the same thing with a set of 5.3s an Manley Pro Flo 2.02"/1.575" valves.I should have flow numbers soon and we'll see???
I agree with the flow under the curve being more important. If you take the valve timing event and express it on a time plot you'll see the valve spends very little time at max lift. All your power is made before max lift especially important is flow when the valve just opens and the chamber gets a charge of A/F in. Of course it's all tied together and more complex then I can explain.
All that being said, I'm not sure how your numbers are, I would have expected a little more flow...t I'm doing the same thing with a set of 5.3s an Manley Pro Flo 2.02"/1.575" valves.I should have flow numbers soon and we'll see???
04-10-2005, 09:43 AM
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Ferrea valves.i knew i was going to lose some peak flow by maximizing the low-midlifts and keeping the runner size down,but didn't expect to have them backup as much as they did.i'm running a small cam(.224dur. at .050,.576lift).i think it will still work good with the heads as i'm not worried about flow past .600
04-10-2005, 12:17 PM
#5
Sorry I haven't had time to respond to your PM...
While these heads are certainly an improvement over stock, I feel there is something wrong with the port shape if in fact they do fall off before .500 valve lift....this of couse is assuming the numbers are correct. Even some of the smaller, more conservative ported factory castings I have seen are usually able to hang on till around .550....perfect for your average street cam .580 or less. Tell your porter to look at the short turn....it might be "overhanging" the valve job a little and laying it back might solve all your problems....at least get it to stay clean into the mid .500 range. Obviously this is purely a guess (not having the ability to see what I'm talking about), but you might coinsider spending a little more time on them to get the higher numbers cleaned up. I bet its worth another 15+ at the wheels....Even getting it to hold its .450 numbers thru .500 and some change would make a noticable difference in power output.
Good luck....
Tony
While these heads are certainly an improvement over stock, I feel there is something wrong with the port shape if in fact they do fall off before .500 valve lift....this of couse is assuming the numbers are correct. Even some of the smaller, more conservative ported factory castings I have seen are usually able to hang on till around .550....perfect for your average street cam .580 or less. Tell your porter to look at the short turn....it might be "overhanging" the valve job a little and laying it back might solve all your problems....at least get it to stay clean into the mid .500 range. Obviously this is purely a guess (not having the ability to see what I'm talking about), but you might coinsider spending a little more time on them to get the higher numbers cleaned up. I bet its worth another 15+ at the wheels....Even getting it to hold its .450 numbers thru .500 and some change would make a noticable difference in power output.
Good luck....
Tony
04-10-2005, 02:53 PM
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Originally Posted by Tony Mamo @ AFR
Sorry I haven't had time to respond to your PM...
While these heads are certainly an improvement over stock, I feel there is something wrong with the port shape if in fact they do fall off before .500 valve lift....this of couse is assuming the numbers are correct. Even some of the smaller, more conservative ported factory castings I have seen are usually able to hang on till around .550....perfect for your average street cam .580 or less. Tell your porter to look at the short turn....it might be "overhanging" the valve job a little and laying it back might solve all your problems....at least get it to stay clean into the mid .500 range. Obviously this is purely a guess (not having the ability to see what I'm talking about), but you might coinsider spending a little more time on them to get the higher numbers cleaned up. I bet its worth another 15+ at the wheels....Even getting it to hold its .450 numbers thru .500 and some change would make a noticable difference in power output.
Good luck....
Tony
While these heads are certainly an improvement over stock, I feel there is something wrong with the port shape if in fact they do fall off before .500 valve lift....this of couse is assuming the numbers are correct. Even some of the smaller, more conservative ported factory castings I have seen are usually able to hang on till around .550....perfect for your average street cam .580 or less. Tell your porter to look at the short turn....it might be "overhanging" the valve job a little and laying it back might solve all your problems....at least get it to stay clean into the mid .500 range. Obviously this is purely a guess (not having the ability to see what I'm talking about), but you might coinsider spending a little more time on them to get the higher numbers cleaned up. I bet its worth another 15+ at the wheels....Even getting it to hold its .450 numbers thru .500 and some change would make a noticable difference in power output.
Good luck....
Tony
04-10-2005, 08:58 PM
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Taking the ramp on out will be another way to increase the .450+ numbers too. Probably take it up to 275 or better on the top end numbers and only add 3cc to the port.
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04-10-2005, 10:13 PM
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thanks for the feedback guys,i appreciate it.i noticed a flow sheet of a stock ls1 head(from JRP's faq page)that backed up a little around the same lift range too.
04-13-2005, 03:57 PM
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Originally Posted by ssheets
All that being said, I'm not sure how your numbers are, I would have expected a little more flow...t I'm doing the same thing with a set of 5.3s an Manley Pro Flo 2.02"/1.575" valves.I should have flow numbers soon and we'll see???