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

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   Is there a rule-of-thumb/formula for header pipe diameter to engine size? (normally asperated). Just wondering.   

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Gerald Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Groupie Joined: 18 November 2003 Location: Canada Online Status: Offline Posts: 53	Quote Reply 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.

tweakedscoots Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 25 February 2009 Location: harrisburg pa Online Status: Offline Posts: 8	Quote Reply 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

Powergreed Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 02 January 2009 Location: Ohio Online Status: Offline Posts: 61	Quote Reply 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.

jackinzoar Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Senior Member Joined: 19 November 2003 Location: United States Online Status: Offline Posts: 7593	Quote Reply 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

Dave A Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Senior Member Joined: 01 November 2005 Location: VA, US Online Status: Offline Posts: 431	Quote Reply 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.

Gerald Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Groupie Joined: 18 November 2003 Location: Canada Online Status: Offline Posts: 53	Quote Reply 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!

lbrown Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 05 February 2007 Location: United States Online Status: Offline Posts: 42	Quote Reply Posted: 30 December 2009 at 9:53pm
	there are many formulae for calculating pipe size . you can google for those free. you can also download a free 10 day trial of engine analyzer 3.5 and work on your whole combination on the computer. you can`t trust engine analyzer like gosipel but it does a lot of calculations for you. the manual will explain most everything you need to know about pipe sizing.
	lwb

bypass Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 08 January 2010 Location: australia Online Status: Offline Posts: 6	Quote Reply Posted: 08 January 2010 at 5:54am
	worked in a muffler shop for on 30 yrs and made heaps of pipes on cars bikes an boats rule of thumb we used an we ade loys of drgsetups was header pipe same size as outlet of exhaust port then on normally aspriated make pipes no longer than 23inches an collet into a merge collector . on harleys we done 1inch 3/4 on most evo shovels sportys as they were that size outlet then made pipes upto 33inches an collected them . on strokers we would step pipe size up to 1inch 7/8 or 2inch avout 7 inches after the port . size of pipe was determined by size stroker kit . dynod a heap an was pretty close on the dollar most the bikes we ran wit vance werent as good as hooker pipes on harley as for nos /turbo/supacharged motors just get the cas out quik as yo can .
	no such word as cant just keep trying

lbrown Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 05 February 2007 Location: United States Online Status: Offline Posts: 42	Quote Reply Posted: 10 January 2010 at 1:13am
	engine size and rpm are the most important factors in determining pipe size. cam timing also has an effect on length. 300 ft per second is the is accepted as the critical velocity . size the pipe for that velocity at the torque peak for a broad power band or size for that velocity near the power peak for a strong hp peak but narrower power band. those formula`s are available or you can can use many available programs to calculate that for you. we used engine analyzer to calculate the pipe needed on our lsr 2000cc production pushrod hd. we had to hide the change from 1.75 pipe to 2.0 behind the heat shields. in production (scta) every thing has to apear stock. that worked well as we made over 160hp with a pushrod 110cu in dyna that apears completely stock . we set the record at bonneville at 153.325mph. the bike has been over 160mph at sea level.
	lwb