another question, am i putting these in the right place?? (headers)

[nizmo]

hi again, im not sure where on this site i should be asking all the questions??? any way just wanting to know if any one had fitted or known someone who has fitted semi tuned headers, i have a set of stainless ones and am not sure if i want to fit them, i have herd they can crack?? and it it going to be worth while? i was told i would gain 4 - 6 kw??

[BC5RA]

Yes and no.

They can crack depending on quality/brand/installation.

As for power gains you generally push the power band up the rev range and gain about what you have quoted, you also may find it will ramp onto boost slower, but other have installed and report faster spool.

Bank on heat wrap no point installing them without it.

[nizmo]

awsome thanks, i had a look on how to fit them tonight when i built the rest of my exhaust and that up pipe looks tight to get to at the turbo end, ill give it a go, thanks

[Lynx]

 BC5RA said:

Bank on heat wrap no point installing them without it.

Hey, sorry to be a noob, but why is there no point installing without heat wrapping them?

[wrx_lou]

Factory manifolds have heatshields. Aftermarket do not.

[kamineko]

well thats one issue

generally you heat wrap headers to retain the heat of the pipe, hotter gas flows faster, they work better after coming to temperature and heat wrapping slows the cool-down

factory headers (well part of them) are solid cast steel. these take awhile to heat up but hold the heat well.

however i only notice a difference on track, when everythings good and hot after constant flogging

[Simon C]

I've just changed my headers. Lots of things to think about.

1) Equal length vs unequal length. Equal length will sacrifice the boxer sound of your engine, and you'll sound like an Evo or a Honda. However, the volumetric efficiency of your engine will be better, as you won't have exhaust pulse interference, and the pipes will be tuned to improve exhaust scavenging from your cylinders. I'm also told that your cylinder temperatures will become more uniform, apparently one of the cylinders tends to run hotter with the factory manifold on.

2) 4-2-1 vs 4-1. 4-1 design is more common for aftermarket headers, I think it's cheaper to make and favours maximal flow for high end power, at the expense of spool + low/mid range torque. 4-2-1 favours better exhaust pulse scavenging at low and mid RPM is better on 4-2-1, so you should expect better off boost performance and spool, but not as much maximum HP.

3) Heat wrap vs non-heat wrap. Heat wrap will retain temperature in your header pipes, keeping your exhaust temperatures high and therefore gas velocity. This is better for volumetric efficiency of your engine and to spool your turbo faster. It won't give you an advantage at the top end of your rev range, as this'll be limited by your turbo compressor wheel once the turbine blade velocity reaches sonic speeds. Downsides are that it will absorb moisture and promote rusting of your headers. The extreme metal temperatures will exaggerate normal thermal expansion and contraction, therefore promoting stress fractures and cracking. Some manufacturers will void the warranty if you wrap their headers. Finally, if oil or anything flammable leaks onto the wrap, the high metal temperatures will ignite it and cause an engine fire, which will be difficult to put out.

4) Materials. Stainless steel is generally the way to go, as it resists corrosion. However, not all stainless steel is the same grade metallurgy, there's cheap rubbish and there's good stuff. Also, thicker metal will weigh more but will be less vulnerable to cracking, especially if the welding is of good quality, and the flanges will be less likely to warp and leak. Beyond stainless steel, you're talking titanium or inconel or other exotic metals which are the territory of WRC and F1 car budgets.

5) Installation. Can be done at home, but it's not straight forward. The major issue is the uppipe, which is a pain in the ass. Most headers have the uppipe as a separate piece, which makes life a lot easier, but my headers and uppipe came as a single piece. If it's a tight fit, you may have to undo your engine mounts and jack your engine up to clear the cylinder heads.

I have Syms 4-2-1 equal length race headers on mine. I lost my boxer noise, but spool is 200rpm earlier and it pulls harder at all revs. I don't think it's worth the effort on an otherwise stock engine, but I'm doing mine as part of a comprehensive powerup, so I expect it to be worth more once I change my turbo and get a retune.

[nizmo]

wow thanks very well explaned. it will give me something to think about, thanks,

[Ryan]

I've got those stainless semi tuned headers on mine, eveyone comments on how good it sounds, especially under load, however performance wise I'm not sure as I put them on the day i got the car.

[D-Style]

Just buy a V8 or later Subi and you have them from Factory.

[wrx_lou]

 D-Style said:

Just buy a V8 or later Subi and you have them from Factory.

Cause thats a cost effective way of doing it.

[DAKRNK]

i am really really after some equal length headers, and i cant find any ANYWHERE, help?

[Guest]

 DAKRNK said:

i am really really after some equal length headers, and i cant find any ANYWHERE, help?

redline performance, 41, either of them will be able to get you some.

-smurff

[wrx_lou]

 smurff']

[quote name='DAKRNK said:

i am really really after some equal length headers, and i cant find any ANYWHERE, help?

/quote]

redline performance, 41, either of them will be able to get you some.

-smurff

Redline dont seem to have any on their website at the moment. just the semituned GC8 or GDB and twinscroll

[Guest]

 wrx_lou']

[quote name='DAKRNK said:

i am really really after some equal length headers, and i cant find any ANYWHERE, help?

/quote]

redline performance, 41, either of them will be able to get you some.

-smurff

Redline dont seem to have any on their website at the moment. just the semituned GC8 or GDB and twinscroll

doesnt mean you cant email them asking :P

they had some nice headers in there on the weekend, didnt pay any attention to what they were though, but they were shinny

-smurff

[wrx_lou]

 smurff said:

doesnt mean you cant email them asking :P

they had some nice headers in there on the weekend, didnt pay any attention to what they were though, but they were shinny

-smurff

true true. should be able to get the xforce ones in anyway.

[Guest]

In an ideal world you would use equal length headers but on the std subaru it doesn't work out that way.

The factory header gets the gasses to the turbo as quickly as possible and goes a good job of keeping the heat in. Aftermarket headers with there longer path and complex twists and turns loose quite a bit of heat in the process. Lost heat / velocity = lost power.

So what we gain with a better design we then lose some of those gains with less heat and gas velocity. Which is why you don't get big gains from aftermkt headers.

[Guest]

could use ceramic heater radiators to keep the piping nice and hot

http://www.elstein.com/products/FSR-1-electric-IR-radiator.php

-smurff

[Guest]

will the v8 headers bolt straight up to my v4? I can get them from my flat mate, but is it worth the change? the engine is out at the the moment so no problems with fitting

[wrx_lou]

they are different where they meet the turbo.

[Simon C]

You'll need a twin scroll uppipe and a twin scroll turbo to use that header. Pity, the OEM Subaru twin scroll header is a very nice piece, comes with heat shields and everything.

[wrx_lou]

 Simon C said:

You'll need a twin scroll uppipe and a twin scroll turbo to use that header. Pity, the OEM Subaru twin scroll header is a very nice piece, comes with heat shields and everything.

and tuned length already.