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Old 08-19-2008, 06:55 PM   #301
ronoverdrive
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Originally Posted by Zac86 View Post
nope that car has the stock headers.
Stock headers until 06 where UEL. 06 and up have EL.
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Old 08-19-2008, 09:22 PM   #302
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are you sure? I have a 98 and mine are EL
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Old 08-19-2008, 11:48 PM   #303
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Yup I'm pretty sure of it. Did you buy the car used or new? Because I remember seeing a thread on the RS25 forums where people were getting OEM and JDM EL headers for their GC's for a cheap performance gain.
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Old 08-20-2008, 12:29 AM   #304
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Yup Im sure. And why do you think yours are EL
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Old 08-20-2008, 08:52 AM   #305
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As far as I know (and it appears to be the case visually), my '99 EJ22 Impreza came with equal length headers. I've read it several times as well. The unequal length headers have the burbling sound to them as the pressure waves from the combustions collide at the collector, which mine has never had.
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Old 08-20-2008, 02:24 PM   #306
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Originally Posted by neilschelly View Post
As far as I know (and it appears to be the case visually), my '99 EJ22 Impreza came with equal length headers. I've read it several times as well. The unequal length headers have the burbling sound to them as the pressure waves from the combustions collide at the collector, which mine has never had.
-N

Nope. Yours did not have equal length exhaust manifolds. Unequal length headers make noises that yours don't because they are headers and because they are also a different pattern of unequal length pipes.
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Old 08-20-2008, 02:50 PM   #307
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Nope. Yours did not have equal length exhaust manifolds. Unequal length headers make noises that yours don't because they are headers and because they are also a different pattern of unequal length pipes.
I'd question your definition of headers then. From what you're saying, you consider "headers" something that you pay for and an exhaust manifold just something that comes on cars stock? Even with my single-port heads, I'd consider the stock piece to be headers because the cylinders firing don't join up in the exhaust stream until they get to the single exhaust pipe. A manifold would have all the cylinders joining up right after leaving the engine. Even on the single-port heads, the two cylinders sharing a pipe on each side are never firing at the same time, so they aren't really sharing volume at the same time.

And next time I'm under there, I'll take a measuring tape to the pipes to see if they are equal length. They may not be ideally shaped, but they sure do appear EL to me. There's an extra kink added into the "shorter" side explicitly to even out the lengths.
-N
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Old 08-20-2008, 02:56 PM   #308
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Aren't manifolds usually cast whereas headers are of tubular steel construction?
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Old 08-20-2008, 02:57 PM   #309
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Originally Posted by neilschelly View Post
I'd question your definition of headers then. From what you're saying, you consider "headers" something that you pay for and an exhaust manifold just something that comes on cars stock? Even with my single-port heads, I'd consider the stock piece to be headers because the cylinders firing don't join up in the exhaust stream until they get to the single exhaust pipe. A manifold would have all the cylinders joining up right after leaving the engine. Even on the single-port heads, the two cylinders sharing a pipe on each side are never firing at the same time, so they aren't really sharing volume at the same time.
-N
I said nothing of the sort and would appreciate if you didn't put words in my mouth. I said that the factory exhaust manifolds are not headers. I did not say why or why not. But I'll just leave you to your own devices. I don't really have the energy to argue with someone over the definition of a header on the internet. Maybe someone else will feel like debating minutae with you...

Though I would be very interested to see how an engineer would manage to get both banks of cylinders on a flat 4 joining up right after leaving the engine. I'm just saying...
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Old 08-20-2008, 02:58 PM   #310
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Aren't manifolds usually cast whereas headers are of tubular steel construction?
Among other things.
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Old 08-20-2008, 03:02 PM   #311
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Maybe someone else will feel like debating minutae with you...
*Raises hand*

Wiki sez:

"Exhaust manifolds are generally simple cast iron units which collect engine exhaust and deliver it to the exhaust pipe. For many engines after market high performance exhaust headers (also known as extractors in Australia) are available. These headers consist of individual primary tubes for each cylinder, which then usually converege into one tube called a collector."

In my exposure, exhaust manifolds don't have collectors. They have "merges", where there is not as careful a design as to the angle, diameter, and length of the merge. Headers have specially designed collectors that are meant to give the least flow resistance while allowing proper scavenging.

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Old 08-20-2008, 03:02 PM   #312
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I've said it before, I've always thought it was strange that people classified the pre-06 headers as "unequal length". The dual port ones basically have no primary tubing - the primaries are maybe 4 or 5 inches long. The difference in lengths of the secondary tubing can't be more than a couple inches, probably a 5-10% difference. For OEM exhaust, that's pretty good.


When I think unequal length, I think of my old Mustang shorty headers. Here's what the stock ones look like:

(Hopefully that image pops up, I can't actually see it here at work.) Note that the front primaries are twice as long as the rears.

Compare the stock Subaru header to a Borla header and that's unequal length. The primaries look to be roughly the same, but clearly the secondaries are waaaay different - one side is about 3x as long as the other.

(Thank you for the picture, Xcceleration.com).

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Last edited by Patrick Olsen; 08-21-2008 at 11:39 PM.
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Old 08-20-2008, 04:37 PM   #313
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Thats the exact same as I have except mine is single port and yes it's EL beacuse I sound like a honduh
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Old 08-20-2008, 07:23 PM   #314
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Read his post. If I understand corrctly, he is sayig they are UEL because there is a few inches of a difference. So if those are the ones you have, they are UEL.
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Old 08-20-2008, 09:42 PM   #315
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yea well those "few inches" dont give any boxer rumble to my exhaust. They are EL.
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Old 08-20-2008, 09:55 PM   #316
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Quote:
Originally Posted by fastenova View Post
*Raises hand*

Wiki sez:

"Exhaust manifolds are generally simple cast iron units which collect engine exhaust and deliver it to the exhaust pipe. For many engines after market high performance exhaust headers (also known as extractors in Australia) are available. These headers consist of individual primary tubes for each cylinder, which then usually converege into one tube called a collector."

In my exposure, exhaust manifolds don't have collectors. They have "merges", where there is not as careful a design as to the angle, diameter, and length of the merge. Headers have specially designed collectors that are meant to give the least flow resistance while allowing proper scavenging.

Aaron
OK, so Borla and replica "headers", AND OBX EL "headers" aren't headers then? They certainly dont give the "collector(s)" careful design or any type of design at all. they just narrow the two pipe into one as cheaply as possible.

Also, the Burns engineering company calls their collectors "merge collectors" and the rest of the industry seems to refer to the Burns style collector as a "merge collector"... of which a careful design and some serious fabrication go into making a supremely efficient use of exhaust gasses. If anything isnt an "exhaust manifold" its a set of headers made by Burns with their collector design. for our engines, only TWE uses such a design in their product. (that I know of)

I think you guys are giving this use of nomenclature too much thought. I would bet a mojority use of the word "headers" in aftermarket engine parts is marketing. If there is no quantified definition for what are headers and what is an exhaust manifold, then who really cares which word is used to describe?

Last edited by RaceFaceXC; 08-20-2008 at 10:00 PM.
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Old 08-20-2008, 10:18 PM   #317
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Quote:
Originally Posted by bulletproof4130 View Post
If I understand corrctly, he is saying they are UEL because there is a few inches of a difference.
I'm not sure how you got that idea.

Quote:
Originally Posted by Patrick Olsen View Post
I've said it before, I've always thought it was strange that people classified the pre-06 headers as "unequal length".

When I think unequal length, I think of my old Mustang shorty headers. Note that the front primaries are twice as long as the rears.

Compare that to a Borla header and that's unequal length. The primaries look to be roughly the same, but clearly the secondaries are waaaay different - one side is about 3x as long as the other.
Are the stock headers perfectly equal length? No. But IMO they're pretty damn close to equal length, much more so than what I consider to be unequal length headers (as exemplified by the Mustang headers and the Borla header).

Pat

Last edited by Patrick Olsen; 08-21-2008 at 11:35 AM.
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Old 08-20-2008, 10:22 PM   #318
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Originally Posted by Zac86 View Post
yea well those "few inches" dont give any boxer rumble to my exhaust. They are EL.
Stock exhaust doesn't give any boxer rumble either. Borlas + random tech catalytic converter + mid-pipe and can = true boxer rumble.

Stock just sounds like, well, nothing.
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Old 08-20-2008, 11:55 PM   #319
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Stock exhaust doesn't give any boxer rumble either. Borlas + random tech catalytic converter + mid-pipe and can = true boxer rumble.

Stock just sounds like, well, nothing.
True, but in VA = defective equipment ticket!!! WTF??
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Old 08-21-2008, 12:04 AM   #320
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Originally Posted by RaceFaceXC View Post

I think you guys are giving this use of nomenclature too much thought. I would bet a mojority use of the word "headers" in aftermarket engine parts is marketing. If there is no quantified definition for what are headers and what is an exhaust manifold, then who really cares which word is used to describe?
On NASIOC? Never!
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Old 08-21-2008, 08:37 AM   #321
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Originally Posted by Matt Monson View Post
I said nothing of the sort and would appreciate if you didn't put words in my mouth. I said that the factory exhaust manifolds are not headers. I did not say why or why not. But I'll just leave you to your own devices. I don't really have the energy to argue with someone over the definition of a header on the internet. Maybe someone else will feel like debating minutae with you...

Though I would be very interested to see how an engineer would manage to get both banks of cylinders on a flat 4 joining up right after leaving the engine. I'm just saying...
I was questioning why you thought the stock headers weren't headers and that they'd have the boxer rumble if they were headers. I wasn't trying to argue - you were calling me wrong and giving a BS reason.

The stock headers on mine are equal length (I will measure to confirm) and are made from steel tubing as oppose to cast iron and don't have all exhaust ports just dumping into a massive collector like an exhaust manifold. I would say that a 4-cylinder boxer can't really have a typical exhaust manifold, as you so keenly pointed out, though the new Subaru exhausts that curl around the front of the engine for emissions stuff seem to be Subaru's attempt at getting them to behave more like manifolds.
-N
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Old 08-21-2008, 10:34 AM   #322
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I told you there were plenty of people who wanted to discussion the minutae with you. You can direct all further comments in their general direction...

But for the record, claiming that a length difference of several inches still qualifies as equal length is ridiculous.
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Old 08-21-2008, 12:10 PM   #323
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Originally Posted by Matt Monson View Post
But for the record, claiming that a length difference of several inches still qualifies as equal length is ridiculous.
So what is the difference in length? Has anyone ever actually measured? I just don't think the difference is enough to be worth worrying about.
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Old 08-21-2008, 01:36 PM   #324
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So what is the difference in length? Has anyone ever actually measured? I just don't think the difference is enough to be worth worrying about.
Exactly my point. Afterall, EL or UEL it's hardly a high performance part.
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Old 08-21-2008, 01:53 PM   #325
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Exactly my point. Afterall, EL or UEL it's hardly a high performance part.
With us single-port header guys, there is no performance part out there. I've toyed with the idea of having a custom set made, but ultimately, I think so long as you're going for NA power, the bottlenecks are elsewhere. I had a very unrestricted exhaust on my engine after it was built and it really didn't feel smooth or torquey until I added at least one resonator into the mix. That suggests to me that exhaust really won't get you much more than a sound until you're really pushing the envelope anyway.
-N
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