Posted By: JERICOGTX
Header building formula? - 08/31/20 04:28 PM
Is there an online program for figuring out the proper header size for an engine? Tried finding one, but not having any luck.
Thanks.
Posted By: an8sec70cuda
Re: Header building formula? - 08/31/20 04:36 PM
I seem to recall a bunch of people here using Pipemax.
Posted By: JERICOGTX
Re: Header building formula? - 08/31/20 05:03 PM
I seem to recall a bunch of people here using Pipemax.
For $150, I'll just SWAG it... Ouch.
Posted By: Al_Alguire
Re: Header building formula? - 08/31/20 05:05 PM
Someone here has pipemax, maybe Mr P?
Posted By: HardcoreB
Re: Header building formula? - 08/31/20 06:46 PM
I get one sized for you LMK via FB...I thought Wallace had one?
Posted By: polyspheric
Re: Header building formula? - 08/31/20 07:04 PM
Primary ID?
Step?
Primary length?
How big is the exhaust valve?
Posted By: LA360
Re: Header building formula? - 09/01/20 04:25 AM
Email me the details on the engine Jeff, and I will run it through Pipemax for you
la360racing@gmail.com
Cheers
Posted By: Hemi_Joel
Re: Header building formula? - 09/01/20 05:00 AM
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.
Posted By: AndyF
Re: Header building formula? - 09/01/20 05:23 AM
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.
Posted By: AndyF
Re: Header building formula? - 09/01/20 05:32 AM
Posted By: JERICOGTX
Re: Header building formula? - 09/01/20 11:39 AM
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.
Posted By: CJD AUTOMOTIVE
Re: Header building formula? - 09/01/20 01:07 PM
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.
Posted By: jlatessa
Re: Header building formula? - 09/01/20 01:19 PM
Wow, is that ever a good read, thanks for the link Andy.
Joe
Posted By: polyspheric
Re: Header building formula? - 09/01/20 02:38 PM
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".
Posted By: AndyF
Re: Header building formula? - 09/01/20 04:24 PM
That is true. The exhaust flange on a Mopar is angled slightly so if you're building custom headers you have to decide if you want the tubes to be perpendicular to the flange or if you want to have the tubes continue the flow. The cheap and easy way to make headers is to make them perpendicular but that might not be the best way on a Mopar. The dyno headers I use have the tubes coming out of the flanges at a slight angle. Those headers really work well but I can't say they are the "most perfect headers ever". I've done my share of header testing and most of the stuff I see kills power but sometimes you'll find something that actually works pretty well. Schoenfeld dyno headers usually make really good power but of course none of them fit in a car.
https://www.schoenfeldheaders.com/sprintdyno1.html
Posted By: moparpollack
Re: Header building formula? - 09/01/20 07:26 PM
Posted By: LA360
Re: Header building formula? - 09/02/20 03:16 AM
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.
Posted By: HardcoreB
Re: Header building formula? - 09/02/20 12:06 PM
Based on your 'goals' and combo pipemax generated 2 1/4" @34-36" and 4" coll @ 18"
Posted By: fbs63
Re: Header building formula? - 09/02/20 02:48 PM
Wallace Racing has a calculator but PipeMax is the best.
Posted By: Chief
Re: Header building formula? - 09/17/20 11:53 PM
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
Posted By: J_BODY
Re: Header building formula? - 09/18/20 12:06 AM
You’re just gonna shove em out the front fender like all the cool kids anyways.....
Posted By: JERICOGTX
Re: Header building formula? - 09/18/20 02:02 AM
You’re just gonna shove em out the front fender like all the cool kids anyways.....
The Road Runner had fender well headers on it almost 50 years ago. I spent a lot of time and money on correcting the hack job to do that mod. No way, no how, am I cutting one single hole in that car to fit headers.
Posted By: Leigh
Re: Header building formula? - 09/18/20 12:26 PM
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
I need to re-route one tube for steering link clearance. That link looks like the answer. Thanks!
Posted By: JERICOGTX
Re: Header building formula? - 09/18/20 01:13 PM
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
Thanks for the link. I like the U bend cutting fixture. Might have to buy a couple different ones.
Posted By: GomangoCuda
Re: Header building formula? - 09/21/20 07:47 PM
Have you seen this article?
https://www.musclecardiy.com/perfor...tem-math-build-high-performance-engines/Written by John Baechtel. He talks a little about the different programs available and then explains how to calculate header dimensions using formulas from Jim Mcfarland. Checked dead nuts against one of John Kaase's engine masters entries.
Also some of David Vizards books cover exhaust tuning.