No guys I was just sauing I can't chat as much at work as there "cracking down" on internet uses thats all. Anyway Madjack beat me to a whole lot it would seem. I would just have to add a few notes to his allready excelent descriptions. Dual diameter or stepped headers are used in an atempt to improve both low end and upper rpm horsepower. Tri Y or 4-2-1 headers use alternating exhaust pulses to create negative presure on an opposeing cylinder to help draw the exhaust out of the engine as opposed to it just being puhed out these are what NASCAR uses almost exclusively
because of this power building feature. Tri-y's are deff without a doubt the way to go but I don't know anyone who makes them fr our engines, If anyone does please post so we'll all know thanks. The biggest benifit from a header is its uniformity all the tubes are the same diameter and are of a larger diameter then the passage ways in most exhaust manifolds smoother flow means less resistance to the gases being able to escape so it makes more power. Always try to get headers with primary tubes that are as close in size to the exhaust valve or bigger that way the exhaust can just flow ut that much easier. Also to port match the head and header with the gasket this way you can open up the path as much as you can again this helps flow which makes more horeses. Woo Hoo !! Did I miss anything?




Semper Fi SAINT. May you rest in peace.

Very good descriptions guys, bravo. Have you ever heard of anyone including a split-runner type design, and using butterfly valving to designate between two different paths? This would be similar to what you'll see with inatake manifolds on (from my experience) old JDM DSM engines (referred to as a cyclone manifold I believe), Yamaha V6 SHO engines (used on late 80s-mid 90s Taurus), and Audi 2.8s. One runner path is longer than the other, which is short/stubby to allow the best of both worlds. The design would be a little different though, as you wouldn't be able to use any type of chamber to distribute the collective air.
Just a thought.

Oh yeah, anyone on turbo manifolds?


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I give man haven't heard of a duell path header. Where it sounds intreging I seriously
think it would be a nightmare to design or God help you actualy build the thing. As for a
turbo header most are very short runners as the turbo mounts right to it and theres just not enough room to do much with it. But from what I remember from my turbo Trans-Am days the path leading up to the turbo doen't mater near as much as the rest
of the exhaust system. Not to say its nothing to be worried about at all its just that thats the presureized side of the exhaust and as long as its free flowing then the over all design doesn't really matter.




Semper Fi SAINT. May you rest in peace.

OHV notec wrote:Very good descriptions guys, bravo. Have you ever heard of anyone including a split-runner type design, and using butterfly valving to designate between two different paths? This would be similar to what you'll see with inatake manifolds on (from my experience) old JDM DSM engines (referred to as a cyclone manifold I believe), Yamaha V6 SHO engines (used on late 80s-mid 90s Taurus), and Audi 2.8s. One runner path is longer than the other, which is short/stubby to allow the best of both worlds. The design would be a little different though, as you wouldn't be able to use any type of chamber to distribute the collective air.
Just a thought.

Oh yeah, anyone on turbo manifolds?

So what your saying is design something to tune your exhaust on the fly. Switch from one header to the other with the flip of the switch or possibly by setting a tension spring to two two butterfly valves to essentially change the flow at a certin exhaust flow? That is if I am understanding what you are saying and or asking. If it was an on the fly design like this what issues would this create computer wise? I mean would the car freak out at the sudden change in exhaust flow? I am sure it could be programed to deal with this kind of issue with a lot of work. So the short runners would take the regular path and the longer runners could come off at the downward bend of the short runners the longer runners then could join in at the collector and head out of the car? I am sorry if i am totally off the wall and this is not what you are saying at all but its kinda the way I read it.

Michael Woolever wrote:So the short runners would take the regular path and the longer runners could come off at the downward bend of the short runners the longer runners then could join in at the collector and head out of the car? I am sorry if i am totally off the wall and this is not what you are saying at all but its kinda the way I read it.

I think you have the general idea here. I'll photoshop a quick diagram when I get home this afternoon. Also, the valve would probably be easiest to program with an RPM window swith and a small electric motor on the butterfly shaft assembly or something. Say, have it switch from the long runners to the short runners at peak torque RPM (as given by tube diameter formula). This would essentially draw out the torque curve to get the best of both worlds (more so than the multiple diameter approach).
Yes, this would be a PITA to weld up, but maybe a good summer project next year


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You're more likely to see the type of header you're asking about on factory cars due to costs associated with design and production. These days, the factory engineers are using smaller engines and trying to widen the powerband as much as possible to make up for lack of displacement. A multi stage system, though not necessarily complex, will need to be built well to be durable. I feel that aftermarket manufacturers aren't producing these headers because they believe they're not cost effective. And unfortunately, headers combined with catalytic converter equipped full exhaust systems really lose effectiveness compared to open headers.

I think many headers on street cars release more power simply by providing a less restrictive flow path than a factory manifold. With tube lengths and diameters designed to fit inside an unmodified or slightly modified car, often having to fasten to the factory exhaust pipe without disturbing the location of the catalytic converter, and with collectors consisting of nothing more than a wide spot at the bottom of the header for a flange or ball and socket joint, there's little chance that most street headers are actually effective at providing true scavenging.

-->Slow

Yeah, it might be a little pricey, but I think the benefits would have to be seriously weighed, especially with engines getting smaller like slowolej said.
Well, here's what I got (didn't think it'd be worth it to make it look pretty...patent pending )

Now, as previously stated, this would allow you to have two completely different headers. The red is to represent the exhaust flow, the green is to mark possible collector locations (just to show they could be at different locations). Obviously nothing is even close to being to scale, I just wanted a visual for what I'm thinking about.
I was already thinking about designing a variable length intake manifold (probably won't do it for the 2.2 though), but this would be a nice addition to the project.
The little mock-up in the botom right is to show how two sets of butterflies could be used to increase durability, and make the overall design more simple (but parts costs would obviously be higher).


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I dont think it would be that hard to weld.... i think there are going to be serious issues with sealilng the inactive route.... and not creating a place for the exhaust flow to be disrupted to much.....

Ok how about this? What effect if any would squared pipes instead of rounded on the exhaust header have on flow?

There would be some really tight corners to weld in, and fitting the pipes together would be a nightmare.
The butterflies wouldn't have to seal as well as, say, a TB plate, because if a little gas gets by it's not a big deal, especially on the top-end.
Squared runners wouldn't work because the exhaust ports are round, and the transition would cause a crap load of turbulence. Not to mention, you can't really bend the square pipes


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Who said anything about bending square pipes? I am thinking you could take and cut stainless sheet metal cut it up and weld it back together. Then use a flaper instead of butterflies like in the first set of pictures.... You could cut a piece to look like the header cut that up to be less restrictive. Then pieces that look like the pics up above weld the other pieces to them... then you get boxes.... its just a thought..... but i didnt know what kind of effect it would have being squared.....

Very intreging idea. I'm just not too sure its benifits would justify its cost to develop and manufacture. this is why most manufacturers compromise on header design to a degree.




Semper Fi SAINT. May you rest in peace.