so why won't TWE headers work with the EJ22?

[Wiscon_Mark]

Is it because TWE is dual port only? (all EJ25s are Dual)

Just curious...

[BAC5.2]

Could be that, that some EJ22's are single port and they don't want to deal with it.

Other than that, they will work on the EJ22. If every other EJ25 header works with the EJ22, then so will this one I'd imagine.

[Wiscon_Mark]

that's what I thought...mine are dual port, so I'm good to go when I start making some money...(which'll be after college :lol:)

[badbasser98]

aren't the TWE's equal length? and if so.. that will kill the boxer sound every subie enthusiest should enjoy :wink:

[belladonna]

matt, you are correct, TWE's are equal length...

[BAC5.2]

Stock N/A headers are equal length also....

Stock Turbo headers are unequal. That's why the Turbo cars ALWAYS sound a little more lopey at idle and under load.

[Sarra]

Stock N/A headers are equal length also....

Stock Turbo headers are unequal. That's why the Turbo cars ALWAYS sound a little more lopey at idle and under load.

Unless you have an exhaust leak, then you get a lopey sound at idle. :(

[Svenerachi1]

wait, my headers on a 99 USDM Legacy GT are equal length????
like the dude said, isn't the unequal length header what creates the sound all of us have come to love???

[Wiscon_Mark]

no, I believe the sound has a lot more to do with the metal used than it does with the flow dynamics. And it wouldn't be something so simple as "equal vs. unequal"

Borla uses a hard stainless steel. Thus, a lot of sound transfers to the tailpipe.

TWE uses a much softer stainless, which is more resistant to cracking (like the borla tends to do) so I would think that softer metal would change the sound.

Stock headers are equal, that's what I was trying to BB98 that one time...

[Huffer]

The factory header's aren't TRUE unequal. They are a compromise between cost and engineering. Sure, they could have given us true unequal (pulse synchronizing) headers from factory, but that would have added several lengths of material AND pipe bending costs.

Might not seem much on a per car basis, but multiply that out over millions of production runs - and you see why Coke shaved 1mm off their labels and saved $1.2mil off producing the "buddy" bottles. ;)

Any unequal header attempts to pulse-match exhaust gases to keep velocity high - but as RPM's vary, getting a compromise is tough.

The higher cost of the TWE items I believe is based on their materials, not necessarily the accuracy of the design.

Mark - have you any information about the materials used? According to TWE they use T304 stainless steel, are the Borla's mild steel?

The best header you could use would be some kind of dynamic system where the merge collector varies it's exhaust distribution path depending on the engine RPM...to maintain consistent exhaust velocity! :D

[scottzg]

no, I believe the sound has a lot more to do with the metal used than it does with the flow dynamics. And it wouldn't be something so simple as "equal vs. unequal"




eh?

it is something so simple as equal vs. unequal.

[badbasser98]

@ Huffer :

I believe that Borla also uses T304 SS...

<goes to double check now :lol: >

-BB98


Yes, The Borla's are T304SS. :wink:

[voorhees]

so who wants my 17183 Borla for $250

[Wiscon_Mark]

The factory header's aren't TRUE unequal.

you mean true equal?

@ scotty: the reason I bring up equal vs. unequal, is because TWE makes both (I think) and I hear that all of their headers dont' sound as good as borla.

Here's an article I read about choosing headers:
http://spda-online.ca/modules/newbb/vie ... 58&forum=9 (http://spda-online.ca/modules/newbb/viewtopic.php?topic_id=58&forum=9)

[Huffer]

Yeah, sorry Mark, TRUE EQUAL.

Either way, they're a compromise.

I'd take TWE stuff over Borla anyday - money aside, I've heard both product types on similar cars, and frankly, the TWE (even their prototype "H" style headers) are MEAN. It helps that it's fitted to an NA car that hangs with the STi's in the autox groups.

[shooter]

Now showing my ignorance :( other than the sound side of matters surely for low/mid range torque a 4-2-1 would be the best design, and for out and out power a 4-1.??

From motorcycle racing and looking at car racing in general all the top teams / manufacturers are using equal length headers rather than the sort after unequal Subaru.

So what am I missing? is it purely a sound issue? A flat four is still 4 pots and so must follow the same exhaust flow as all other engines??

[Huffer]

I don't think the term "equal" can truly apply anymore - because the actual length of the pipes does and can differ. I think the term equal refers to the amount of time between exhaust gas pulses passing a certain point and being merged. I might not be right on that, but it's a plausible use of the term.

Shooter - there is some good info regarding the type of merge collectors on the Cobb website, and also TWE (which I believe use a 4-1). I may be incorrect.

[BAC5.2]

Borla's crack because the two drivers side pipes were welded together, and would crack at the connector.