Of course, but if you are tuning your subaru, I would say that sound is less important than speed. Otherwise you would go for a decat exhaust and the std unequals....

I fail to see GT spec 2s as a compromise, they are unequal through and through and will behave as one...

Unequal become quite restrictive at 350+ if the americans are to be believed. And I for one totally agree.

 

Banny, if you had equal that could have been 700hp, that is the difference, it might not have been restricted, but with equals it could have been improved further

 

Quite possibly, may get to find out this time

 

If I was looking for as much power as poss, but wanted to keep unequal headers, what do you think would be the max bhp I could expect to be looking at??

 

As banny said, he was running 666hp out of his unequals, I was running 517 out of mine, but they will all succumb to heat stress and crack etc, that isnt the manifold design, that is poor 304 stainless grade used to make the manifolds.

Since changing to equal length manifolds (517hp on an s206 turbo and a 2.1 stroker built 20k miles ago) my power went from 450hp on low boost to 485 and 517 to 535.

So just by changing manifolds gaining 35hp on 99 fuel and 17 on 10% meth.

I also have now found out this was on a knackered turbo, with oil seals, cracked wastegate, cracked compressor housing and generally broken. So there might have been some more to be had, either way the gains are impressive at that kind of power level just from changing from unequal to equal headers

 

Im intrigued to know more details about this power gain.
The original lower figures, were they the figures from 20K ago ?
Was it mapped by the same person ?
Was the car dynoed before and then after on the same rollers on the same day ?

 

Yes they were the figures from the original build 20k ago, (450/517) just after run in when it should have been at its "peak"

Those 20k miles have been driven how it was meant to be driven, track days, drag days etc. So in theory it should have only gone down.

On the day I upgraded to alkatek (from simtek) got the manifolds fitted etc Im pretty sure Martyn said it pulled 411hp with no meth but this was with the equal manifolds on the existing map as the previous headers were so cracked they werent serviceable.

Its been done on the same dyno at engine tuner (who havent changed or modified it in any way shape or form) by Martyn since it was built.

The main change is how it drives,

 

The thing is every car is different and gains will also differ from car to car....

I have rcm equal length manifolds which have been fine so far....and that's at a competitive level....I think there less prone to cracking due to the collector design over the unequal length gt spec headers.

Inconel would be the best material for headers...

 

Care to expand on how the collector design would affect this?

From my research it is to do with the heat capacity of each metal, they have a temperature range at which the structure of the metal starts to change, 304 stainless has quite a low operating window and when this is exceeded this will cause the manifold to become brittle and the engine vibrations finish it off.

I have Titanium manifolds on my car and the operating temperatures of this grade will far exceed what a turbo car can put out.

 

They fail at the welds ime.....

I'm not saying your titanium headers are not up to the job.

Just the material of choice is Inconel ... ?


Thought you had 321 stainless steel headers not titanium ?

Titanium would be a small fortune !

 

Yes they will always fail at the weakpoint. and the welds should not be the weak point. My 304 stainless failed at numerous points.

Titanium is cheaper than inconel, and 321 is titanium steel. not stainless.

 

is it true to say theres little point in buying aftermarket headers for a twin scroll sti (hawk or similar)

 

Titanium is about 8x the price of 625 Inconel ....

Killer b state it's 321 stainless steel ?

Which is stabilized with titanium for its heat properties..... Not made from titanium.

 

Correct, I believe tim h of jti had some tomei aftermarket headers and they were poor in comparison to the standard jobbie

 

So after all that his manifold isn't made from Titanium after all ???

 

Its Titanium steel 321 stainless as per the website, It is stainless alloyed with titanium.

Not that it really matters as t is designed specifically for this application out of far superior material that wont crack

And the material wont affect the performance... It is the design!

 

No it's not titanium matty.....would cost more than the car was worth !

It's 321 stainless steel.

 

Dude not to get into this again but you're a stubborn one, you would not back down on the 2.8bar boost when countless people said it maybe wrong.

You only let it go once Martyn advised differently, you seem to be doing the same again when its in black an white that the killer bee headers are 321 stainless steel.

 

Interesting thread. I'm gonna buy new headers for my 450hp 2.1L scdb Type R v5. I've been looking around but couldn't decide what to buy. But after reading this thread i'm certain that i'm gonna buy equal length headers. And maybe i should save some money and get the killer b ones. They look stunning and looks like it performs really well also. And it should be long lasting since it is higher grade steel as pointed out in the thread.


http://www.killerbmotorsport.com/index_files/Header.htm

 

Actually Banny, as discussed at the time that is what I was led to believe. And it was 2.7bar I was under the belief of. And I posted at the time the message I received from martyn Ill go through and find it again if we are going to keep bringing this up? So what I was wrong, and either way it doesnt matter, to be honest it made it better the fact that I wasnt running as much as I thought, so Im not upset tbh!

Right, and what is 321 stainless? It is stainless alloyed with Titanium. Titanium steel as it is most commonly referred to. Which is the term I have been using.

I fail to see how the material actually matters we were discussing performance gains, I dont think aluminium, steel or gold would make a difference

 

Dude no need to get defensive, no one is out to prove you wrong

 

Do it, You will not regret it. They just ooze quality, once you get them unpacked I left them on my coffee table for a week just as an ornament lol!

Well it does sometimes seem like a personal attack

 

You're in good company, you're a knowledgable guy which can only benefit the rest of the board. Never take anything on here to heart as its just the tinterwebz

 

So are you going to order a set then?

 

Defo going equal length this time but need to save some pennies first for the engine and box

 

I can imagine. I got their baffled sump, baffled windage tray and oil pickup and they look great.

 

321 grade stainless steel is actually 304 grade stabilized with titanium.

The killer b headers look very good quality ... And the material is undoubtedly better than the 304 grade most use.

 

Soi much for not going for big power this time

 

Ballcocks !
Restrictive my ****.
I'll grant you, I was very impressed after my initial "What's this ****" response when faced with the killer B headers,
but to say something starts to become restrictive at 350bhp yet produces this is laughable.

I've ran the GT spec headers for years and years, yes they're a compromise when it comes to cost over reliability, but certainly no compromise on bhp per £

 

I've had my GT Spec headers fitted since 2006/7 and they haven't self destructed yet.