Horsepower gains from headflow CFM differences??
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TECH Junkie
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From: At the office
Horsepower gains from headflow CFM differences?? I see people with GTP heads getting up to 325+ or so cfm intake flow at .600 lift.
My heads only flow 306 cfm at .600 lift.
Assuming the same flow benches, equal exhaust flow, and equal velocity, how much of a hp difference would there be between the 2 different types of heads if the hi lift intake flow #'s are about 20 cfm more on the GTP heads and about 10-15 cfm more at midlift???
Keep in mind I'm talking stock displacement using a TR 230 cam for reference.
<small>[ August 11, 2002, 09:46 PM: Message edited by: verbs ]</small>
My heads only flow 306 cfm at .600 lift.
Assuming the same flow benches, equal exhaust flow, and equal velocity, how much of a hp difference would there be between the 2 different types of heads if the hi lift intake flow #'s are about 20 cfm more on the GTP heads and about 10-15 cfm more at midlift???
Keep in mind I'm talking stock displacement using a TR 230 cam for reference.
<small>[ August 11, 2002, 09:46 PM: Message edited by: verbs ]</small>
Staging Lane
Joined: Apr 2002
Posts: 69
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From: AUSTRALIA
Re: Horsepower gains from headflow CFM differences?? Back to back inhouse testing has proven that you will get no gains- Once they flow good and you port some more & get better flow - you will get no gains - I know its hard to believe but its true - jees I was pissed off afer spending so much effort to make the heads better and be rewarded with no gains...... <img border="0" title="" alt="[Mad]" src="gr_images/icons/mad.gif" />
Stay with your current heads unless your going to fit an even larger camshaft etc
Stay with your current heads unless your going to fit an even larger camshaft etc
FormerVendor
Joined: Nov 2001
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From: Houston, Tx.
Re: Horsepower gains from headflow CFM differences?? It depends on what components are limiting your system but heads CAN make around 2 hp per cfm in very general. It doesn't mean they will however.
TECH Fanatic
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From: Objects in mirror no longer matter.
Re: Horsepower gains from headflow CFM differences?? Like Erik said, there is much more to making power in cylinder heads than just flow numbers. You will be very happy with your heads, don't worry <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
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TECH Junkie
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From: At the office
Re: Horsepower gains from headflow CFM differences?? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Fenris Ulf:
<strong>Like Erik said, there is much more to making power in cylinder heads than just flow numbers. You will be very happy with your heads, don't worry <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'm not too worried about the heads. Just more curiousity as to how much a difference cfm makes.
<strong>Like Erik said, there is much more to making power in cylinder heads than just flow numbers. You will be very happy with your heads, don't worry <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'm not too worried about the heads. Just more curiousity as to how much a difference cfm makes.
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
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From: Texas
Re: Horsepower gains from headflow CFM differences?? The rule of thumb for potential power is 2.15*CFM on a V8.
The intake and such on the LS1/LS6 are a restricton once you get over 300cfm.
Also, beware of flow numbers that don't come from the same bench. They don't mean nearly as much. They are just like dyno numbers which can vary dyno to dyno.
If flowbench X is on the conservative side and flowbench Y is on the liberal side. Well, you could see a couple of % differences. Plus the orifice size, and was it done @ 25" or 28".....
Anyhow, if your heads make 308 then potentially they could make.
662.2
For a set making 325+
698.75+
You are looking at about 6% difference
The intake and such on the LS1/LS6 are a restricton once you get over 300cfm.
Also, beware of flow numbers that don't come from the same bench. They don't mean nearly as much. They are just like dyno numbers which can vary dyno to dyno.
If flowbench X is on the conservative side and flowbench Y is on the liberal side. Well, you could see a couple of % differences. Plus the orifice size, and was it done @ 25" or 28".....
Anyhow, if your heads make 308 then potentially they could make.
662.2
For a set making 325+
698.75+
You are looking at about 6% difference
