Headers - BMW Forum

Kevin325i · 05-09-2004, 12:17 AM

Anyone know if stock M3 headers will bolt up to a '92 325i? Will the downpipes from the M3 also bolt up to my stock 325i exaust? There's a guy on Ebay parting his M3 and so far nobody has bid on the headers in like 3 days, so 60 bucks for some headers with like 60k miles on them sounds pretty good.

If i got them I'd most likely end up going to a shop and getting them ported and polised.

Kevin

dutchbmw · 05-09-2004, 06:48 AM

A M3 has a bigger displacement engine, and therefore it must be a longer engine. The header engine mounts are further from each other than the ones who fit on the 325i.

CiscoKid · 05-09-2004, 07:43 AM

i second that

Furious · 05-09-2004, 09:22 PM

. ive been waiting to see the dyno charts from a friends adventures with buying M3 headers. but from the looks of it right now, id say dont bother.

Kevin325i · 05-09-2004, 09:46 PM

But they fit, correct?

Kevin

thinair · 05-09-2004, 10:01 PM

Ok, to clarify, the m3 engine isn't longer then the 325 engine. Actually if you were to get the 320, 323, 325, 328, 3L M3, and 3.2 M3 US spec engines all side by side without the plastic ignition coil cover you'd probably wouldn't be able to tell the difference between them except which are 91-95 and which are 96-99.

Also, the 325 exhaust manifold is the exact same as the US 3L M3 (1995) exhaust manifolds. They're just cast manifolds.

The 96-99 328/M3 manifolds are welded tubular manifold, but the gains are extremely questionable, and in my eyes certainly not worth going through the trouble of removing the exhaust manifolds to install one that barely flows better.

If you're going to get an aftermarket exhaust manifold get a proper even length manifold, like HIOP, turner, evosport, superspring, kromerkraft, etc. You get what you pay for.

And exhaust manifolds aren't really the first place to start when looking for more engine power anyway, start on the intake side, cat-back exhaust, cams, etc, etc, then exhaust manifolds/headers should be almost last on your list.

007ben · 05-09-2004, 11:18 PM

but exhaust is like the 1st thing all the honda boys do. doesn't that mean we should too...

or maybe we should just get tips like them too..

damn ricers.

El Presidente · 05-10-2004, 12:17 AM

bzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz zzzrrrrrrrrrrrrrrrrrrrr.

At least they don't have whistle tips.

thinair · 05-10-2004, 04:41 AM

Quote:

Originally posted by 007ben@May 9 2004, 11:58 PM
but exhaust is like the 1st thing all the honda boys do. doesn't that mean we should too...

or maybe we should just get tips like them too..

damn ricers.

Yeah, headers are one of the first things that Honda modders do. Why?

- Most aftermarket Honda headers are cheap (unless you want good ones)
- they're really easy to remove (in comparison to BMW headers). The Civic headers for example are right at the front of the engine, it's pretty easy to get to. 8 nuts of the head and voila. The BMW headers are on the passenger side of the engine, you'll probably need to lift the engine to make room to get them from between the engine and the strut tower, and there are 12 bolts, and they're really hard to get to.
- the Honda aftermarket is like the aftermarket for a Mustang or a Camero, there are a lot of companies who make them, and a lot more modders compared to BMW modders.
- many Honda owners (not all) believe random dyno charts that the more questionable companies post, claiming 20-30hp gains from just headers. On BMW's it's proven that even the best header on a mostly stock engine doesn't really give you much gain. BMW knew what they were doing from the factory.

jllphan · 05-10-2004, 08:24 AM

I'm with thinair for the most part.

You would see a difference with the ///M engines, but not the others. The intake is significantly different.

By the way, nice call on the 96-99 thing, the VANOS unit would deffinately give away the later cars....

And you would see a noticeable increase in a dyno or real world driving with ///M headers if and only if...

1. You improved the breathing on the front side (better intake, and CAI)
2. Omitted the cats, and ran a straight pipe all the way back.

Neither of these are cheap, which brings me back to thinair's point, that for the money, you probably wouldn't be happy.

dutchbmw · 05-10-2004, 10:03 AM

Quote:

Originally posted by thinair@May 10 2004, 05:41 AM
Ok, to clarify, the m3 engine isn't longer then the 325 engine. Actually if you were to get the 320, 323, 325, 328, 3L M3, and 3.2 M3 US spec engines all side by side without the plastic ignition.....

?? The bore of the 320i is 80 mm, from the 3.2 M3 the bore is 86.4 mm! This means by an engine with 6 cylinders a extra total width from 38.4 mm! Maybe I am wrong or....

Kevin325i · 05-10-2004, 04:16 PM

The whole reason for this question is to eventually take my engine to (or better than) M3 specs (reason for the '92 non-vanos) I saw some articles online about M3 headers bolting to a 325i. So I wanted to see if you guys knew anything about it. It was just a good thought because of the price so I could just keep it around the house.

To sway things more towards that way, my muffler is shot, so I was just going to go all-out with the exaust from the engine back.

Oh well, I don't really got any money for anything right now

. What cash I have is being put towards chasing the electrical gremlins outa my car.

Kevin