ric

Can someone give me some help in the exact procedure on removing the headers?

I plan to port and flow them (match the holes).

From what I've heard there are 5 holes to match to the gaskets:
4 that come out of the cylinder
1 where the headers go into the turbocharger

Thanks for any information/help
ric

Floyd

iTrader: (9)

Firstly what model car are we talking as I only know about the MY99/00 cars?

You only need to port the headers and make sure that the holes are at least as big as the gaskets. Use the soot marks as your guide for removing material. The up pipe can be tricky to remove apparently due to engine mounts getting in the way. You'll need to undo these and jack the engine up to get the clearance.

I'm not sure how much gain you will get for the effort though, probably best to try the easier options first. Some people have had trouble sealing the gaskets up afterwards as well so this may be a pain to fix.

F

NutterKam

If your heatshields are rusted and falling to bits then it's not too bad because the hardest bit is actually getting these buggers off if they're knackered. The standard manifol comes in 2 bits - a long bit and short bit. Porting is easy cos the material is quite soft but make sure you got more than one set of stones or abrasives costhey get eaten quite quickly! Another pain nut and bolt to remove is the top bolt of the turbo up pipe. Other than it's quite straight forward.

NutterKam

oops... That should say "If your heatshields are "NOT" rusted and falling to bits..."

duczz

Have many people done this mod? what are the benefits and are there noticable gains to be made?...

dowser

Did anyone heat-wrap the headers as well? Is it something that should be done, or can they then get too hot?

Also, anyone recommend an EGT kit with probe to mount in the headers at the same time?

Sorry Ric!

Thanks
Richard

NutterKam

Scoobymania do an Autometer EGT gauge kit which costs around 85 squid but it's in Farenheit rather than Celcius.

BugEyed

Richard

You will not gain any power by lagging the exhaust manifold, but you might reduce noise slightly, particularly if you've got replacement stainless parts. However, the downside is it is likely to pick up all sort of cr*p and end up smelling / smoking.

Andrew

Ah, the great port matching debate begins again. Steps in exhaust ports can be a good thing, provided the step is to an increasing size and not a reducing size. Hence you would grind you manifolds to the same or a larger size than the ports in the head.

I have seen stepped port sizes used very effectively in racing engines, but particularly so on long stroke normally aspirated ones. In these engines it seems to give better exhaust tuning effects "off cam", allowing you tame a "wild" cam more easily. However, on a restrictive exhaust they have less effect, and seem to work less effectively on short stroke engines. All of which is a long way of saying I don't think you'll find a difference on a Scoob!

Duncan

BugEyed

Andrew

Thanks for the compliment.

I think I might have left you with the wrong impression - matching the ports is a good idea, I'm just unconvinced that opening up the headers beyond the size of the exhaust ports may not give any further benefits.

Duncan

NutterKam

I don't think there's enough material to open them up beyond the size of the exhaust ports without danger of the header falling apart...

AndrewC

Is it generally accepted that porting the headers can reduce EGT?

If so then it would certainly benfit anyone running increased boost on a std turbo and i/c.

Andrew...

dowser

Thanks Duncan

I've been reading Corky Bell, hence the question - he suggests keeping as much heat (ie; energy) in as possible from the engine to the turbo is 'a good thing'.

I was just concerned whether the stock cast headers could deal with the additional heat.

I'll be lagging my d/p though, especially to reduce the noise (it's ss ) - is there a brand of lagging that's better than others?

Thanks
Richard

mutant_matt

BugEyed,

A friend has an STi and has just taken off the HKS un-equal length headers and the difference (downwards ) in power, torque and most of all, drivability is quite a shocker!!!!!

I don't know whether or not the HKS headers have steps but I don't think so which implies that there *are* gains to be had from porting the headers/getting a decent set of headers.

Bear in mind that if you make the headers more free flowing, you may well have to increase the fueling as this usually makes the car run leaner which may be unsafe.

Matt

JamesS

Had the headers off twice in the last week. Should take no more than 1-2hours. Remove the undertray and spray all the bolts with easing agent and leave. Uppipe removal requires either turbo off, or jack the engine of its mounts. I had the turbo out.

The n/s headers need much more work than the o/s. The o/s headers arn`t that bad.

Don`t bother with the link pipe as you will create an expansion pocket within the join - bad!.

Don`t bother with the uppipe either - Its a manky piece of ****. Get a new one from Scoobysport for the 01MY (it fits early cars).

I`ve mounted an EGT sensor in this new uppipe just prior to turbo.

Effect - IMHO the most surprising benefit was a significant improvement in the driveability of the car. Small throttle openings in traffic that previously caused drivetrain oscillation and some thumps etc was amazingly smoothed out. Got better low end responce from the turbo, better flow at the top and the exhasut noise was smoother but deeper. Excellent mod.

Then fitted the HKS headers (hence twice in a week!).

Lost some bottom end responce, but bloody`ell hit 3500 and then again at 5000....and the noise, the noise...........

BugEyed

James

What sort of HKS headers did you go for? I'm tempted by the equal length one, but like the boxer noise.

Cheers

Duncan

mutant_matt

Don't think HKS do equal length headers - they are un-equal length (which you, debatably, want over equal).

Matt

NutterKam

I'm pretty sure HKS do equal length cos I was looking at one when I was over in the far eats recently.... soooooo tempted but managed to resist! If they're not equal then they'd be pretty close to equal...

JamesS

The one I have is not equal length. The chap I bought it of thought it was. Its not far short.

Sounds like Jason out of Friday13th is lurking under the bonnet with a 2-stroke buzz saw!!!! And LOUD.(with full SS)

BugEyed

James

Thanks for the answer - your description is superb!

Matt

What are the benefits of unequal length over equal length?

Duncan

mutant_matt

As I understand it, equal length headers will give you a bit more power but they will also move the peak torque further up the rev range. Rather than having four seperate torque pulses with the current header design, you get one larger one. Arguably, this is a good thing if you do lots of track driving and peak power is king. However, if you want the widest torque curve possible then this is not such a good thing. IMHO, drivability (and low down grunt) is king and I would much rather have a lower peak if it meant a higher range - if you see what I mean.

A friend of mine bought what he was told were HKS equal length headers for his STi V but as at the time HKS didn't make equal length, they were un-equal length. I have to say, I was very impressed with the improvement in drivability and torque. One downside is (depending on your viewpoint), that will a full decat, the increase in noise is significant. My friend lives 30 houses away down the street and I can hear him start his car up

When he comes home from work, driving at 20-25mph round our backstreets, I can hear him coming from a couple of streets away and that's when he's keeping the revs below something like 3000rpm!!!!

Sounds great but I couldn't live with that kind of noise.

Matt

P.S. Still pretty sure that HKS don't make ELH but will let you know if I can prove/dis-prove this.....

AndrewC

I though having a clean step between the exhaust ports and the headers had a beneficial effect, just something I read (probably on here) about research done years ago which proved that it was a good thing.

Andrew (also thinking about getting his headers done)...

[Edited by AndrewC - 4/10/2002 12:24:31 PM]

AndrewC

I bow to your superior knowledge oh great BugEyed one

Andrew (still thinking about getting this done)...

[Edited by AndrewC - 4/10/2002 12:55:53 PM]