Header questions

[PeaveyBassist]

What are the advantages/disadvantages over short headers and long headers? I am talking about headers like the IE Shorty headers and the Stahl/BavAuto headers. What differences are there in the 2 performance wise?

Will

[NC325iC]

well i think the short ones are close to equal length and the long ones are equal length and equal length is better, im not sure why though if anyone wants to shed some light on that

[permit]

Equal length has something to do with equal amounts of back pressure into the engine...I really don't know that much about it, thought I had heard something like that once.

[nando]

one of them makes your wallet a lot lighter than the other. :D

[Jordan]

The reasons behind wanting the tubes as long as possible (within reason is to keep exhaust velocity up)

Shorter primaries work well for lower RPMs, since the exhaust isn't moving as fast. At higher RPMs, this begins to restrict things a bit; longer primaries are ideal.

It all really comes down to exhaust gas velocity, which directly effects scavenging.

Long, equal length primarys are ideal. Each primary should be the same size as the exhuast port exit, if not slightly larger. Too big will result in a loss of velocity and reduced scavenging.

Ceramic coatings also help. The coating keeps heat in the primarys where it belongs, not radiating off. The hotter the gas stays, the higher the velocity.

Thats what I know.

[PeaveyBassist]

So the longer ones that are equal length are better. But the IE Shorty headers being $260, BavAuto's longer ones are $600, and Stahl's from IE are $800. That being said, the shorty ones would be the most bang for the buck I am assuming. Shorter primaries will help low end torque and hp and not get as much a gain at higher rpms but still better than stock correct?

Will

[Jordan]

I don't honestly think the IE shorties will provide much to any gain on a otherwise stock m20b25. Like it or not the stock exhaust manifold flow just fine for the engines stock output.

Hell I'm making 206hp/213tq and I haven't even touched my exhaust system yet.

I would say grab the IE shorties just for looks, but they don't even look good...



If you still insist on getting IE's shorties, opt for the ceramic coating. At least then they won't rust and look like shit.

Once you add up the cost of the shorties, ceramic coating, and shipping.. might as well buy BavAuto's...

Lets put it this way, I get just about anything from IE at cost. I could have had the shorties so cheap I can't disclose, yet I still passed on them.

[CarsSuck]

I cant really say anything about the BavAuto M20 headers, but my dad ordered a set of their M10 headers and they weren't very good. It was a few years back and I dont remember the complete details. Something with the manifold gaskets blocking the primaries. Anyways, my dad sent them back and bought Stahl headers from greenfield. They fit perfectly and perform great. You can also get them in a smaller primary thats more appropriate for the street than the 1.5" that IE sells.

[PeaveyBassist]

So basically... IE Shorty headers suck... and if I was even planning on getting headers I should just wait and save money to get BavAuto's or Stahl or something of that nature correct? Thanks for the help so far Jordan. I appreciate it.

Will

[Jordan]

We use the 1.5ID Stahl headers on all our m10 race motors.

They are badass.

[JRKOUPE]

Stahl have been around a LOOOONG time........at least 30 yrs. Everyone raves about them.
I just spoke to IE today about the shorty's!..of course they state they will be an impvt over stock( and I think they would be) but there are no dyno's to prove it. Headers in general will show biggest gains on hot motors. BUT...I have also been talking to some1 who runs the IE's and he says you feel the impvt over stock above 4500 rpms and they sound great.I agree w/ Jordan on his comments, altho I like the look of the shortys myself over stock. But we are all mod addicts.....hell, the IE appeal to me for the price alone... I have also heard good things about port matching the oe exhaust mani.....but if you are not doing it yourself, the time and labor may be more than the IE's......

[Slick92GS-R]

well, i was given the choice of stock manifold, IE shorties and the stahl $600 headers .... i went with the IE shorty's..
--- u don't need a dyno or any opinions to see that this would obviously improve the motor's ability to breathe. its also lighter than a stock manifold and at around $250.. how can u go wrong ?
--stock manifold is certainly a more congested design.
as for a $600 set of headers on an M20..? maybe on some kinda stroker motor w 12:1 compression and a nasty cam... but why build a m20.. hello? - better off to find an yourself an M3 motor --

i agree on getting ceramic coating applied --

[nefarious7907]

well, i was given the choice of stock manifold, IE shorties and the stahl $600 headers .... i went with the IE shorty's..
--- u don't need a dyno or any opinions to see that this would obviously improve the motor's ability to breathe. its also lighter than a stock manifold and at around $250.. how can u go wrong ?
--stock manifold is certainly a more congested design.
as for a $600 set of headers on an M20..? maybe on some kinda stroker motor w 12:1 compression and a nasty cam... but why build a m20.. hello? - better off to find an yourself an M3 motor --

i agree on getting ceramic coating applied --

why build an M20? maybe you should think about that comment a little/alot more. The factory headers actually flow pretty well, not great but not horrible either, and I noticed no one has brought up MSDS headers which I believe are mid length(sold through pelican). I know Jordan has more than enough reason why to build an M20.

[joshh]

Headers are made differently for different applications.
Theres way more to it than just the length of the primaries. I can get (or you can find) you all kinds of technical information if you'd like.

[Digitalwave]

well, i was given the choice of stock manifold, IE shorties and the stahl $600 headers .... i went with the IE shorty's..
--- u don't need a dyno or any opinions to see that this would obviously improve the motor's ability to breathe. its also lighter than a stock manifold and at around $250.. how can u go wrong ?
--stock manifold is certainly a more congested design.
as for a $600 set of headers on an M20..? maybe on some kinda stroker motor w 12:1 compression and a nasty cam... but why build a m20.. hello? - better off to find an yourself an M3 motor --

i agree on getting ceramic coating applied --

I think that with a stock-ish M20, this guy is 100% right. You won't notice much if any difference between shorty and long headers. Shorties for the money aren't bad, they look better than stock and are A LOT lighter (I used to own a set). Couple them with a single 2.5 or 3" exhaust and you can save a lot of weight overall.