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header size-to-engine size - rule of thumb?

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Gerald View Drop Down
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Joined: 18 November 2003
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  Quote Gerald Quote  Post ReplyReply Direct Link To This Post Topic: header size-to-engine size - rule of thumb?
    Posted: 05 November 2009 at 11:49pm
Is there a rule-of-thumb/formula for header pipe diameter to engine size? (normally asperated). Just wondering.   
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tweakedscoots View Drop Down
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  Quote tweakedscoots Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2009 at 9:12am
Burns exhaust.com  Go to their site and they have some great software that you can access. Header size ,length,angle of megaphone size angle reverse cone etc.
redundant
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Powergreed View Drop Down
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  Quote Powergreed Quote  Post ReplyReply Direct Link To This Post Posted: 07 November 2009 at 8:20pm
Pipe Max 3.6 Google it. Don't know if it works but someone put alot of effort into it. It is quite a bit more capable than I original thought when I purchased it.
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jackinzoar View Drop Down
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  Quote jackinzoar Quote  Post ReplyReply Direct Link To This Post Posted: 07 November 2009 at 9:32pm
true minimum is ID of valve seat , honest minimum is mating surface at the head ,, might be times where your porting-guru requires a tapered head pipe ,, reverse cones are a bandage just as megaphones are ,, you wont find either on a PS car or nascar and they are eons ahead of bikes
street cars kill bike racers
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Dave A View Drop Down
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  Quote Dave A Quote  Post ReplyReply Direct Link To This Post Posted: 07 November 2009 at 11:34pm
Unless you are running a professional class and/or trying to set a record, up to SuperComp run the VHR sidewinder (~$225), TopGas or better run a ProPipe (~$300-350 used) or a new one (you can still find the older version for $500)
That new stainless VHR ProPipe, that you weld yourself, for Pro Stock or ProMod only, it's way too pricey. 
They all are sized real close for your application in either case.
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Gerald View Drop Down
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  Quote Gerald Quote  Post ReplyReply Direct Link To This Post Posted: 08 November 2009 at 4:07pm
Thanks guys! I was just curious as I have a couple different project bikes here, different motor sizes, and some header choices too. I have a standard pro-pipe-sidewinder, a PCO sidewinder, and now a 'spyder'-prostock pipe.
I used to run a 1428-car-tire GS thats been 8.80's, I ran it with the V&H PCO pipe (1-5/8" tubing, spigots) and it worked fine.  
Recently I picked up a new V&H 'pro-stock spyder' pipe (NOT the newest stainless-weld yourself one, the TRAC-style one) it's dimensions are 1-3/4" tapered to 1-7/8". This should work fine on the 1428, and that is where it will end up, but I have a street-project GS here thats only 1133cc, and I was eye-balling/test-fitting this spyder pipe on it. I'm pretty sure that is too big of a header for that small of an engine, but this is what got me to wondering if there was a 'rule-of-thumb' for header size-to-engine size.
Thanks again for your help!
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