header gurus

[Barry Donovan]

I am doing something unique, derived conclusion on my own.. and now second guessing.



This is thick 2 inch for marine use/biodiesel/industrial. 304 stainless, and not cast of course, all weldable. I do not need the threads to work, it was simply a good price threaded.

I have some last venturi on a cylinder head exit, upside down exhaust boxer.. need to remove restriction, and need something outrageous.

I know v8s get darn big, but cannot place where I saw a thick pipe just for a few inches coming out of a cylinder head.

pipe above will be cut in half. 3 inches for each head. The thread part will be going through flange, welded, and into the head, not screwed in, simply fits the hole about 3/8ths above flange as a sleeve. flange welded to the thick pipe.

will this do something crazy like heat soak or something I am missing?



I have got everything correct except the silly incorrect math of Subaru oem has a remnant of my new header, already 2 inch stainless. I think its 1.6 inches or less for a short distance. I was mistaken to think it needed it. it cannot hold a seal even sunk into the head port snugly. Too much restriction.

I am simply snipping all that top part off, going with new flanges, mild steel, welded to the stainless cut in half.. I am just curious as to the upside down and thicker steel. the block is a brick, material unknown. With engine running it does not even set off a very sensitive electromagnetic detector. The threads actually gave me some thought as a wire ride for the last electrical energy in each fire. the block being that resistant, the threads are a helper into the pipe.

I am guessing it will be ok, but.. a guru would be great. oh, this is setup for max cfm..hence the drama. this is not an ea82 boxer you find at usmb or Nasioc.

In short..I guess there is some history trivia as well as some advie needed:

• what engine had a thick pipe coming out of every cylinder for a few inches, then off to a 16 gauge normal piping?

• and..upside down thick steel sleeved into head a bit..too much heat going to be kept?

[Beagle]

I am doing something unique, derived conclusion on my own.. and now second guessing.
...
In short..I guess there is some history trivia as well as some advie needed:

• what engine had a thick pipe coming out of every cylinder for a few inches, then off to a 16 gauge normal piping?

• and..upside down thick steel sleeved into head a bit..too much heat going to be kept?

a) Briggs and Stratton does that and it sucks. Most of the multi cylinder motorcycle junk I worked on from the 70-80's do something similar.

b) Not enough heat to worry about or you have other problems.

bump to the top for you. Header design is a trip. There is a program called Pipemax that you would probably like but it's not free.

http://www.maxracesoftware.com/pipemax36xp2.htm

[JeffMcKC]

I have it and can run it if you want to give up some info on the combination.

[Barry Donovan]

thanks for replies.
I knew I saw that someplace.. motorcycle.
it may have even been on a two stroke engine I rebuilt.

"Do not touch the thicker length coming out of head..do anything you want after that".
a set tuning length for a kawasaki 440.

25 years ago. I am glad I can remember anything at all.

the sube gave me the idea as the head itself tells you it is a two inch port. why Subaru shrink it to less than 1 5/8ths upside down. Smashing an incomplete bursting fire into a dead end road...upside down.

will get that installed.. this also allows me to avoid bridging two long tubes somewhere under the tranny, can keep it all the way it is. As rally animal is the goal in this, one pipe can get smashed and not take out the whole thing.

edit:
another memory revival as to why I wanted huge pipe out of head for some inches. like a two stroke, timing can change. I blame two rubber timing belts.. within that change a very hot fire can happen in bursts. today the cams are beautiful, no sign of that error ever again.. but, I don't forget.

[SuperBuickGuy]

don't put the pipe past the flange - basically, that focuses the hot gasses directly at the exhaust gasket and it'll fail. I did this on my very, very first header; a SL125 Honda. I thought I was being smart (I had to be all of 12, so "smart" is a relative term) by putting the pipe past the flange - it melted the aluminum collar. Once I removed the part that was above the flange, all worked as it should.

As for the 1 5/8 restriction - what is the cross section of the port?

[Barry Donovan]

don't put the pipe past the flange - basically, that focuses the hot gasses directly at the exhaust gasket and it'll fail. I did this on my very, very first header; a SL125 Honda. I thought I was being smart (I had to be all of 12, so "smart" is a relative term) by putting the pipe past the flange - it melted the aluminum collar. Once I removed the part that was above the flange, all worked as it should.

As for the 1 5/8 restriction - what is the cross section of the port?

the port is gargantuate. A 2 inch very slightly out of round, maybe years put it there. the heads are 100k mile.
I simply cleaned it up to be round with a 2 inch holesaw.
the old ea82 heads, those were not two inch, and took a bit of strong arming to drill out.
that is how I knew to go after two inch on the old one.

Today I run the new head, no egr by factory.

I'll take your advice and keep the flange pipe flush, or height of gasket at most see what happens. that is a thick pipe, so giving more room to the head would be a good idea indeed.

if it runs like it does now... I am as excited as a 12 year old to see what a real opening does with fuel air that can actually feed it today. it is quite feisty already.


everything up front, it won't pop a wheelie.

you may vomit a little, but the opening restrictor from old header inside new one, is less than 1.5 inch and jagged ridiculous factory welds. Not a bit of Subaru left at all in this one after this connection. I respected it like a two stroke, as subarus played with two strokes for years. They were just plain wrong on the ea82.

I'll post a pic of before and after in the 5k build thread.