I'm looking for some advice please! I'm looking at 3 options to replace my standard headers:-

Equal length tubular
Unequal length tubular
Ported OEM

Which header option will give best performance upgrade in terms of spool-up and useable power?

Cheers

Greg

 

Properly ported OEM will give a noticable improvement but doing it properly is more than just a Black and Decker and grinding stone. However it can be very cost effective.
Equal length headers do away with the destinctive exhaust note which some regret.
I do not think it is a matter of choosing equal length or unequal but more a matter of choosing a set that are proven to work. I use Ion Spec 4 into 1 and a cheaper alternative that has given good results is Gruppe S.

 

Harvey,

Many thanks for that. Is there an appreciable difference in performance between properly ported OEM headers and the tubular after-market manifolds?

Thanks

Greg

 

I would say there is, having had both.

There is a definite improvement in the top end with Gruppe-S headers from about 5000rpm onwards, but in midrange (3000rpm), i detected a very slight loss in torque (and i mean slight).
The improvement outweighed the disadvantage in my opinion.

There was a thread somewhere on this board with respect to using a smaller bore up-pipe with the Gruppe-S headers and those that mentioned it, preferred this particular option, however, i have no complaints with my "big bore" set.

If at all possible, best bet is to try someone elses car with the components fitted and make a decision but bear in mind their vehicle spec before coming to a conclusion.

Alan

 

Alan,

Thanks for that, appreciated.

Cheers

Greg

 

Basically agree with Alan. My spool was perhaps 150/200 rpm later on tubular but that is not so now due to other mods and mapping. Tubular showed good advantages over ported from around 4.5k up.
Ported O/E=£50. More or less but must be done properly to get all the gains. Gruppe S? £500?
If you can afford it and it fits with your spec then go for proven tubular but you can still get a noticable difference for a bit of effort and not a lot of money with O/E.

 

Harvey,

Thanks once again - some food for thought!

Cheers

Greg

 

Greg - hope you don't mind me jumping in.

Harvey - are you saying that I could get my OE headers ported for £50? If so, does this price just include the porting, not removal and re-fitting?

I am currently driving a MY00 with a full SS system, John Banks TEK2.5, Dawes, K&N panel. Would further ECU mapping be essential for reliability (once the OE headers are ported) or just beneficial in terms of achievable performance gains?

Apologies if the questions are painfully basic but this is a subject I have never researched and am a mechanical dunce.

Thanks

 

Was wondering what is involved in the porting ... just match to gasket outline and remove rough surface/ lumps, or is there an ideal design for original headers?

Neil

 

IMO port the OEM plus aftermarket up pipe!
JIM

 

BTTT to see if we can get a couple of answers.

 

I would imagine a business would charge for the removal and replacement of the headers, as it can be quite time consuming should they come across the usual seized bolts etc etc.

When it ported mine, i ported them out to probably just a little behond the soot marks left by the gasket, and then ported as far into the cast headers as possible. Rough grind first with a die grinder then smooth grind/polish with smaller stone.

You port in the direction you want the air flow to be going.

There is a thread somewhere in projects that goes into it in a little more detail and also has pictures.

Steven

 

I have an engineering shop that port O/E cast headers for me and do other machining.When I talk about headers I am including the O/E up-pipe. Lagging these at the same time, properly also makes a difference. Knowing what to do is part of difference between moderate and good results. £50 is the charge to me and I then spend my own time with a B+D finishing the job off.
If porting on its own is done then I do not think a re-map is essential but there again every time my car is re-mapped after any change we always pick up some more hidden BHP. [We=Bob Rawle on the lap top. I am the monkey behind the wheel with the seat of the pants input]
Oh, I assumed everybody would remove/refit their own headers and then there would be the cost for new gaskets/carriage if not done locally/stripping the headers into component parts and (usually) burning off the heatshield(s) and wrapping so work out yourself if you want to spend money porting O/E or putting into new which can also benefit from porting and wrapping.
Where does it end. Power is not cheap but certainly cheaper the more you do for yourself.

 

Thanks guys.

 

Porting OE headers is definitely worthwhile, even makes the exhaust a bit quieter. It's a slippery slope though - I've been through 3 different sets of tubular headers since porting headers 18 months ago

Pipe diameter is the major consideration IMO; larger diameter will flow better at high revs, but contribute to a higher spool point. You need to consider what you want to use the car for - the best track solution will offer ultimate power, but a narrower useable power band...probably not best suited to the road.

I'm currently using the Maxim equal length on my ej20, but an iON design was also good. The iON is currently being saved for my ej25

Off topic a bit; Harvey - my original iON up-pipe fractured it's flexi-joint at the first track day. Jack sent a new up-pipe. The original up-pipe (light brown ceramic coated jobbie) was narrower diameter than the polished (solid) replacement. However, looking inside the replacement there is a serious, and intentional, reduction in diameter about 15cm's before the turbo (it opens back out to full diameter, and then is nicely flowed into the smaller flange opening for the turbo). The work is very well done (nice smooth changes), and I was wondering whether you've any experience with this design (I assume its to speed gas flow just before turbo)? The reality of trying to fit the new up-pipe to old header means some engineering work is needed, lol

Edited to add: you can get away without a remap when changing to tubular headers, but you should check fuelling carefully if the car is already tuned (especially if already remapped away from stock pig-rich settings ). However, it will likely be lean during spool at least, and you can throw a fair amount more timing at it if it's a good header. Remap required for full benefit, basically

Richard

[Edited by dowser - 10/22/2003 7:39:41 AM]

 

Hi Richard:When I got a second set of headers I noticed the difference in the up-pipe with the deliberate reduced diameter before the exit to the turbo. I was all for getting the Black and Decker out and "improving" it but thought I would ask Ion first and was told it was there to get a final pulse out of the exhaust before the turbo.
Did not make too much sense but decided these guys knew more than me and they would not go to the trouble of putting it there if it did not serve a purpose.
I am not sure when the change was made from 4 to 6 bolt Bellhousings, just know that it was 4 bolt on early cars and mine is a six bolt.
I am sure that Colin will know and is better able to comment on the intrchangeability.

 

Thanks Harvey - yep, I didn't think they'd go to this trouble for no reason.

Re. bolt patterns, I believe it's phase I and II. Certainly my97 Legacy is 4 bolt.

Richard

 

Even after the problems I had with my headers, I would thoroughly recommend them, as the results speak volumes.

Even with a conservative map, my 2002 wrx achieved almost 290 lb/ft torque, which is considerably more than similar spec cars running standard headers, and more even than sti8 PPP's have been achieving.

My spool point is a few 100 rpm later, but it's really not noticeable on the road, and it more than makes up for it once you are going.

After much deliberation, I chose the equal length headers, and although initially I missed the flat 4 burble, I am now utterly addicted to the howl the equal length headers make above 4000rpm.

 

stop it Ed' !!

you are reigniting my enthusiasm for the headers.. which are STILL in transit afaik

 

Can't beat that superbike howl nosie thingy!!!

 

Looking forward to seeing how much louder it gets with a VF35 and 500's

 

dowser - you're still saving those headers for the EJ25 eh? The version you got was specific for the powerband you requested. Design is different then that of the headers that Harvey is running.

Cheers!

Jack
(WWW)www.iONPerformance.com
(email)Jack@iONPerformance.com

[Edited by iON Performance - 10/27/2003 7:10:25 PM]

 

Jack, I'm looking to get some headers, Sti 8. Had a look at the HKS, Gruppe S, Borla, GP Moto but have never seen any iON although I know Harvey makes good use of them

I sense from you thread above you do different versions, can you enlighten me, email if youre not allowed to post.

Cheers

Conrad

 

Hi Jack - good Since you posted first, what's the deal with the new (up-pipe in chrome) to old (header) joint - I have to 're-engineer' the joint...considerably; up-pipe flange bolt holes are 3-4mm offset from header partners.

Richard

 

Greg,

I ran stock ported headers on my car. It was already mapped with a Link and after porting required between 1-3% more fuel depending on the zone due to improved gas flow. Of course this may vary from car to car. If the car is already mapped then as it has been said - watch your fueling carefully.

Rannoch

 

Just one car's results:

Power figures off Delta Dash road dyno (ignore the actual numbers, compare the % increase):

AE802 decat, intercooler/hoses, induction running 14 PSI: 180 BHP, 184 lbft
+ Mapped running 17 PSI: 197 BHP (+9%), 206 lbft (+12%)
+ Gruppe S headers and half turn tighter on actuator (same ECU map) running 17 PSI: 208 BHP (+16%), 222 lbft (+21%)

Interestingly with the graphs overlaid on this car there was no loss of midrange torque by adding the headers (although the original map had already richened a few lean areas), the half turn on the actuator just put the boost back to where it was before the headers, peak and held were similar before/after. In this case the MAF based ECU picked up the difference in airflow quite nicely and things were fine. Not always the case.

[Edited by john banks - 10/27/2003 10:29:34 PM]

 

jb,

was that the big or small bore set?

I am guessing that was a third gear run.IMO it is second that suffers most with headers, if your in third you can drop to second but if your in second you cannot drop.

 

i got some headers for sale,anyone interested?

 

Gruppe-s manifold and up pipe can give 20bhp and 15lb/ft with out even a remap.

 

I would be interested to know how much benefit you would see from ported OEM headers with an aftermarket uppipe.

Andrew...