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Old 01-21-2018, 05:59 PM
78w72 78w72 is offline
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Join Date: Nov 2007
Location: iowa
Posts: 5,598
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Quote:
Originally Posted by Steve C. View Post
CFM flow on the exhaust ports ? At what rpm ?

For interest see posts 9 & 14 for some formulas here:

http://forums.maxperformanceinc.com/...t=David+Vizard


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sorry i have no idea on exhaust cfm flow on my heads. they are out of the box stock round port 72cc e-heads & usualy shift points are around 5500-5800 rpm.

thanks for the links, i read those threads & saw the graph... but graphs are not always 100% accurate nor do they apply to every engine combo the same. also 1 or 2 posts down "taman" says he uses 1 3/4 headers & hes making a little more power than me but ran close to same times before his recent motor refresh. is he loosing hp or tq? i dont know, thats why im curious what others are using or suggest.

sounds like i would get by fine with 1 3/4, tribal tubes suggested a smaller tube header might increase torque due to better scavenging, but at what cost to HP, if any?