Headers
 

Folks, can someone please explain to me the benefit of headers? Do headers=extractors? Are they a worthwhile addition?

To answer your actual question, headers are supposed to be better designed than the standard fitted exhaust manifold. There are two types. Equal length and Unequal Length. Equal length headers have the same distance from each cylinder outlet plummed to the same length, as to get even exhaust pulses through the manifold. Unequal length, is exactly that, unequal (which the standard headers are designed around). They are also usually mandrel bent, which means they have no compressed sections. Their diameter is equal throughout the bends. Effectively increasing exhaust flow, allowing the turbo to spool up faster and increase power and torque. The standard WRX manifolds though are pretty effective up until around 240awkw anyway, so unless you plan on making more power than this, the standard headers will suffice.


I had a set of xforce EL headers fitted to my 2.0L GC8 STi. I didnt notice any increase in power at all (My level of modification was significantly less than 240awkw). What I did notice was a slight increase in bottom end torque before boost kicked in (onboost performance was unchanged). Also my fuel economy didnt really change.
The big change was sound. With the EL headers you will loose that boxer rumble and it will sound more like an inline 4. You can how ever get Unequal length headers and keep the sound. EL headers (in my opinion) are really reserved for high HP applications (above 240awkw, which is a lot of power from a EJ20/EJ25 imho)
I dont think you get any major gains with headers on a WRX with less than 240awkw so money is probably best spent elsewhere like TBE, intercoolers, computer, suspension or brakes.

If you have a stockish wrx/liberty, the best upgrade would be a TBE or a suspension upgrade.



Just my 2c

If you are still considering these, Kando Dynamic on eBay sell decently priced sets, both equal and unequal length. Same factory as Tomei (and the ones Ultrex sold). Really nice quality, comes with all the bolts and gaskets etc.

I've got an unequal-length set waiting to go on mine that I just got ceramic coated so I'll be able to update on how they are once I get them fitted.

David,
What was the power gain after fitting the larger Kando uels and how long they been on?

+1 regarding pants feel better torque down low with EL. Can't say much regarding loss of rumble with EL, however I'm running lumpier cams than normal, giving it a bit of lump at idle, but a more piercing and less sluggish sound in the top end of the rev. range. No power values pre and post headers as it was part of an entire engine build.

I lost my rumble, went back to stock.

Thanks for the input everyone.

Patch I'm sure a number of folks will be interested to know the results do please do keep us updated. David I'm keen to know the answer to the above question too.

teejay did you gain/lose any power when you put them on/went back?

Now that I actually get what headers are for can folks answer this... If I'm getting a good TBE and tune in the near future, can I easily have the headers installed at a later date without modifying the new TBE or anything else? Do they just bolt straight up? Keep in mind I have a 07 Lib GT. Thanks for your patience, I'm enjoying being educated!

[QUOTE=rada;781964]can I easily have the headers installed at a later date without modifying the new TBE or anything else?[/QUOTE]

Not sure how the tune will react but the header/up-pipe combo will replace the engine -> turbo exhaust pipework, whereas the TBE does turbo -> exhaust exit so no interference or issues with headers and the TBE.

honestly mate, at your level of modification i would not waste money on headers. I would only worry about changing headers if your looking for BIG power. a bigger intercooler, more boost and tune would be a much bigger power increase than headers. Im pretty sure others will agree. There are better mods that are more noticeable at the seat of the pants, which at the end of the day is the most important thing.
Dont forget things like brakes and suspension. Cars got to corner aswel.

Go TBE+tune for now.
Then look at changing turbo as an alternative to headers...then later do headers to get more power out of it.

A Blouch Dominator 1.5xtr (if you can afford it) should do the trick really well after the tbe+tune...
Thats where I'm thinking I might invest in with mine... or an AVO/Tomei turbo as cheaper options

Headers or turbo first :-/ I can't decide either

I'm starting to think turbo then headers later to extract more power as you'll always be limited by the stock turbo even with bigger headers.

Research the interweb, lots of info out there on combos that have been tried.

[QUOTE=Patch;781971]Not sure how the tune will react but the header/up-pipe combo will replace the engine -> turbo exhaust pipework, whereas the TBE does turbo -> exhaust exit so no interference or issues with headers and the TBE.[/QUOTE]