Header building formula?
#2815474
08/31/20 12:28 PM
08/31/20 12:28 PM
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Joined: Jan 2003
Posts: 10,027 MN
JERICOGTX
OP
I Live Here
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OP
I Live Here
Joined: Jan 2003
Posts: 10,027
MN
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Is there an online program for figuring out the proper header size for an engine? Tried finding one, but not having any luck.
Thanks.
69 GTX
68 Road Runner
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Re: Header building formula?
[Re: JERICOGTX]
#2815479
08/31/20 12:36 PM
08/31/20 12:36 PM
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Joined: Jan 2003
Posts: 13,365 Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,365
Marion, South Carolina [><]
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I seem to recall a bunch of people here using Pipemax.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: Header building formula?
[Re: an8sec70cuda]
#2815498
08/31/20 01:03 PM
08/31/20 01:03 PM
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Joined: Jan 2003
Posts: 10,027 MN
JERICOGTX
OP
I Live Here
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OP
I Live Here
Joined: Jan 2003
Posts: 10,027
MN
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I seem to recall a bunch of people here using Pipemax. For $150, I'll just SWAG it... Ouch.
69 GTX
68 Road Runner
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Re: Header building formula?
[Re: JERICOGTX]
#2815499
08/31/20 01:05 PM
08/31/20 01:05 PM
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Joined: Jan 2003
Posts: 19,367 Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,367
Las Vegas
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Someone here has pipemax, maybe Mr P?
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Header building formula?
[Re: JERICOGTX]
#2815550
08/31/20 03:04 PM
08/31/20 03:04 PM
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Joined: Oct 2007
Posts: 4,206 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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Primary ID? Step? Primary length? How big is the exhaust valve?
Boffin Emeritus
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Re: Header building formula?
[Re: LA360]
#2815724
09/01/20 01:00 AM
09/01/20 01:00 AM
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Joined: Jan 2003
Posts: 7,490 Minnesota
Hemi_Joel
master
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master
Joined: Jan 2003
Posts: 7,490
Minnesota
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I have pipemax but I'm not smart enuff to figure out how to open it. Bring a zip drive next time you come over.
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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Re: Header building formula?
[Re: JERICOGTX]
#2815726
09/01/20 01:23 AM
09/01/20 01:23 AM
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Joined: Jan 2003
Posts: 31,042 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,042
Oregon
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How good do the headers need to be? If you are trying to grab every last erg of power then you'll need custom headers since none of the factory built headers have a perfect flange. If you are just building a bracket car then factory headers are fine. If you need to custom build headers for fitment reasons then factory style flanges are a decent place to start. If you want to have headers that help the engine make power then the flange and the first few inches of tubing should match the exhaust port exactly. Most off the shelf headers have a large step at the flange which kills velocity at exactly the wrong point. Get that flange correct and you've won a big part of the battle.
If you can have the first few inches of pipe off the head straight then you'll make more power. If you can use large radius bends you'll make more power. One or two step headers will make more power but cost a lot more money and time. I ran 2 inch dyno headers on my race 514 at 900+ hp even though the formula says I could've gone larger. The trick was that they matched the port very well and they were straight off the ports. The TTI headers I have on my Duster make very sharp bends right at the port. Those headers fit in the car but they cost the engine a bunch of power. Of course as Joe Sherman used to say, "I never found any power in the exhaust". Joe had more dyno pulls under his belt than most anyone in the business, header testing rarely finds much power. Power usually just gets lost on the exhaust side.
I've used PipeMax for years. It is a very useful program for a lot of reason other than header design. If you're serious about making power then PipeMax is a good program to have on hand. The cam portion of it is a little odd but the dyno prediction part of it is pretty good. I think it is built on a very solid math model.
Last edited by AndyF; 09/01/20 01:26 AM.
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Re: Header building formula?
[Re: AndyF]
#2815727
09/01/20 01:32 AM
09/01/20 01:32 AM
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Joined: Jan 2003
Posts: 31,042 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,042
Oregon
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Re: Header building formula?
[Re: AndyF]
#2815755
09/01/20 07:39 AM
09/01/20 07:39 AM
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Joined: Jan 2003
Posts: 10,027 MN
JERICOGTX
OP
I Live Here
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OP
I Live Here
Joined: Jan 2003
Posts: 10,027
MN
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I read up on that yesterday. Good info. Thanks for the other info Andy. I plan on buying my stuff through www.racemufflers.com They make different 304 Stainless flanges for BB Mopar heads.
69 GTX
68 Road Runner
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Re: Header building formula?
[Re: JERICOGTX]
#2815776
09/01/20 09:07 AM
09/01/20 09:07 AM
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Joined: Sep 2008
Posts: 656 Florida
CJD AUTOMOTIVE
mopar
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mopar
Joined: Sep 2008
Posts: 656
Florida
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Race Mufflers is Stainless Headers out of Minnesota. They have good US stainless tubing, Rath-Gibson, and their own mandrel bending machines. I use a lot of there tubing based on the quality and price. Burns also uses Rath-Gibson. It is more expensive from them, but the bend quality is also better. Not knocking on Stainless Headers, but the the bend legs are not 100% perpendicular to the radius. That is the difference in price between the two.
Burns has an excellent program, and if you purchase tubing or a flange from them, they will run it for you for free. It is a quite an involved questionnaire about your engine, so have flow numbers, cam spec's, engine spec's, vehicle spec's, etc, available.
Craig Scholl CJD Automotive, LLC Jacksonville, FL www.CJDAUTOMOTIVE.com904-400-1802 "I own a Mopar. I already know it won't be in stock, won't ship tomorrow, and won't fit without modification"
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Re: Header building formula?
[Re: AndyF]
#2815782
09/01/20 09:19 AM
09/01/20 09:19 AM
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Joined: Aug 2009
Posts: 1,317 Ohio
jlatessa
pro stock
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pro stock
Joined: Aug 2009
Posts: 1,317
Ohio
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Wow, is that ever a good read, thanks for the link Andy.
Joe
Last edited by jlatessa; 09/01/20 09:20 AM.
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Re: Header building formula?
[Re: JERICOGTX]
#2815821
09/01/20 10:38 AM
09/01/20 10:38 AM
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Joined: Oct 2007
Posts: 4,206 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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W/r/t exit angle of primary: This presumes that the flange surface is actually perpendicular to the port axis, sometimes they're not. Read Blair on this, the volume, strength, and direction of both pressure waves and actual gas in a V8 exhaust is utter confusion. Many formulas end with "then make it 6" longer, and shorten by testing".
Boffin Emeritus
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Re: Header building formula?
[Re: AndyF]
#2815894
09/01/20 03:26 PM
09/01/20 03:26 PM
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Joined: Nov 2005
Posts: 15,119 85086
moparpollack
Lil Herman
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Lil Herman
Joined: Nov 2005
Posts: 15,119
85086
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56 Plaza 63 D100 step side 67 Coronet, 68 Roadrunner, 69 Super Bees, 69 Coronet 500 convertible, 70 Roadrunner Post, 79 D150 360, and a severe case of Mopar a,d,d
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Re: Header building formula?
[Re: moparpollack]
#2816053
09/01/20 11:16 PM
09/01/20 11:16 PM
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Joined: Jan 2003
Posts: 6,142 Melbourne , Australia
LA360
master
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master
Joined: Jan 2003
Posts: 6,142
Melbourne , Australia
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Has anyone found somewhere that custom makes the megaphone for a collector? I remember finding a shop that did, but can't remember what they're called now. It wasn't the usual places like Burns, SPD, Performance Welding etc.
Alan Jones
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Re: Header building formula?
[Re: LA360]
#2822036
09/17/20 07:53 PM
09/17/20 07:53 PM
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Joined: Dec 2011
Posts: 201 Texas
Chief
enthusiast
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enthusiast
Joined: Dec 2011
Posts: 201
Texas
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Has anyone found somewhere that custom makes the megaphone for a collector? I remember finding a shop that did, but can't remember what they're called now. It wasn't the usual places like Burns, SPD, Performance Welding etc. Is this what you are looking for? I've used them several times, good stuff. Cone EngDave
Dave Covey
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