Exhaust Header

Typrus · Post by **Typrus** » Sat Aug 26, 2006 5:26 pm

Alrighty folks. I need your technical experience, and a prayer that this time the browser won't self destruct after 20 minutes of typing.

I want to build a tubular header for my engine. Why? The exhaust mannie from the factory is horribly restrictive, thats why.
So how to attack this?
https://www.headersbyed.com/bildbetr.htm gives many helpful tips.
From the aforementioned site's suggestions, I've concluded that a header length of 32-40 inches would be nominal for our engines. I've also concluded that a 4-2-1 design would best suit the same.
The front tube of our cars is about 37 inches long, with the mannie runners about 10 inches long. This leaves room for a flexpipe before Mr. Kitty, as measured on my 86.
A good 4-2-1 design on our Inline-4's utilizes a 4-2 segment that joins the 1st and 4th cylinder together, and the 2nd and 3rd cylinders together. How long should the 4-2 segment be before it merges into the 2 pipes? In other words, how long should each cyl have its own runner before joining with its corresponding cyl? Then how long should the 2 tubes be before the final collector?

The circumference of the exhaust ports in the gasket corresponds very closely to that of a 1 1/2 inch pipe. Should that be used? But wait... How can that be best when the stock front tube (that carries all 4 cyls flow) is 1 3/8 inch? Would that not harm exhaust velocity? So then what size do we use? 1 inch? 7/8??

Our exhaust ports are closer to this 0 than this O. They are ovalesque. We hardly have room to make the ports round, so the tubing must be alterred. So how do we form the round tube to be ovalesque?
The tubing has to take a rather sharp dive right after the head in order to clear the intake manifold. How can we maintain a mandrel bend considering this? How can we create a oval-round transition considering the bend? Would it be best to transition AFTER the bend?

Where would we mount the O2 sensor? Or the EGR tubing?

I personally have some more research to do, especially if noone has technical input.

This would obviously only apply to N/A applications.

kamiphloj · Post by **kamiphloj** » Sat Aug 26, 2006 6:52 pm

I am not an expert but I will try.I would not use plain old pipe.Try calling some header manufacturers .Try getting them to brag about what theirs are made of.Do a search on MSC.There are a great industrial supplier an you can get 7 ft lenghths of various sizes of 4140 tube from them rteasonably priced.
A dood treatise on some of the port shapes can be found in Smokey Yunick's book "Speed Tuning Secrets"
The oval port has a lot to do with real estate.More room for height.Round is good.
On your question about sizing the tubes,only one cyl at a time is exhausting a pulse.Also remember a small increase in dia is a large increase in area.
One way to form the ends might be to put a piece of 3/4 or so thick plate in a mill and use a tapered end millto millthru so the desired cross section to achieve is on the small end and the large end is just large enough to accept the tube.Draw it,do the trig to get real numbers.Then heat the tube with a weedburner and drive it thru.

Another way would be to dowel together a pair of blocks and mill the desired transition thru them,like a mold with open ends.hese could be put around the tube,then a press or maybe a heay duty vise would form it.
Fore an outcomethe oval should be known and repeatable so you can shape the attaching flanges to fit.Colo Iron and metal has a CNC waterjet cutter that would make the flanges nicely.
People who make headers allready have the tools to do it effficiently.Prototyping from scratch takes a little cut and try and toolmaking.To do it yourself requires creating a process to do it.I have no doubt you can do it.It can be a greater endeavor than paying $1200 (wild guess} to bassanni or thorsen or whoever might custom fab headers to spec.
By the way,across the road from JJ's is a welder If he hasn't retired Phil is not a goosepooper.He is a Tig Master and a gentleman.
I hope someone else can offer you something more useful.kamiphloj

takza · Post by **takza** » Sun Aug 27, 2006 6:11 am

You don't shrink from the difficult jobs...eh Typrus?

It's that transition from the exhaust ports to DOWN that sounds the worst.

shogun · Post by **shogun** » Mon Aug 28, 2006 8:42 am

the guy who does my mufflers said if i wnated to step up from my 3asu manifold that works almos like a header to a real header i should go with 1.5" tube and go equeal length,

Typrus · Post by **Typrus** » Mon Aug 28, 2006 4:19 pm

Heh.... Smokey Unick?
I figured 1.5" might be good.

http://www.classictube.com/products_exhaust.asp
http://www.stainlessworks.net/cart/prod ... ts_id=1340

That kind of tubing? Or maybe
http://www.headersbyed.com

Yeah, the bend is pretty intimidating. Thus the potential idea for a custom intake mannie.
http://www.velocity-of-sound.com/veloci ... foldlg.jpg

http://www.velocity-of-sound.com/veloci ... foldlg.jpg

Fun stuff.

Typrus · Post by **Typrus** » Sun Sep 03, 2006 1:37 am

http://www.team-integra.net/sections/ar ... ticleID=50

Interesting... But is it valid?

I can see how pairing the 360 degree off ones creates the even flow, creating a more constant flow, with no pulse really pulling much more than the other, whereas the cyls 1 and 2 setup creates more suction on the 2nd one and more resistance on the first because in that half-time of stillness, the pulses stagnate more than in an even 1/4 stillness. So which is more worth than the other? Is this just a bunch of Integra people trying to sound smart? I dunno...

Typrus · Post by **Typrus** » Sun Sep 03, 2006 11:39 pm

I need help being able to fill this out....
http://www.burnsstainless.com/Xdesign/R ... __form.htm

So far I have-
1984 Toyota Tercel, Mild Street/Strip
Toyota
1.5L (88.6CI)
3.05 (77.5mm)
3.03 (77mm)
Single Overhead Camshaft
2bbl Carburetor
2
32/36 Weber

So yeah... Especially on the cam stuff, I'm stumped. For either the Schneider OR the stocker.

Gasoline Fumes · Post by **Gasoline Fumes** » Mon Sep 04, 2006 12:32 am

I'd go with the even firing option pairing 1&4 and 2&3. I think most of the better headers are that way.

Maybe a pic of a Samurai header setup that way would be helpful?

Aussie_3ASCV · Post by **Aussie_3ASCV** » Wed Sep 06, 2006 8:47 am

just for any reference i got quoted 650 AUD to get custom headers for 4A. that was 4-2-1 setup down to primary muffler with a low end torque spec to match crow cam for 4A. just a rough quote for anyone

shogun · Post by **shogun** » Wed Sep 06, 2006 8:51 am

right here in guatemala, i have gotten quotes form 150 dollars for a normal one to 300 for a merge collector one with mandrel bends

Rasmus · Post by **Rasmus** » Wed Sep 06, 2006 10:18 pm

and up here in canada, im making one for 50 bucks.

Typrus · Post by **Typrus** » Thu Sep 07, 2006 12:21 pm

Anyone know our cam specs? I need to know to get the info on proper header sizing and so-on.I want to know the stock and the Schneider if we can.

Gasoline Fumes · Post by **Gasoline Fumes** » Thu Sep 07, 2006 11:23 pm

Typrus wrote:Anyone know our cam specs? I need to know to get the info on proper header sizing and so-on.I want to know the stock and the Schneider if we can.

Have you tried asking Schneider? I'd assume they have specs for both.

Typrus · Post by **Typrus** » Fri Sep 08, 2006 12:34 am

Yes. All they keep saying is, "The specs should be on the website soon." Its starting to piss me off.

Typrus · Post by **Typrus** » Sat Sep 09, 2006 1:14 am

Does honestly nobody know?

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