nom

Nope.
You don't want any back-pressure behind the turbo, & that's that.
I really need to find the plot that has the <3,500 info accurate, I think

Deep Singh

Getting a feeling of deja-vu

john banks

Take some Sumatriptan fast then sleepy boy.

Razor2001

No back pressure after the turbo ? I thought that it was proven that if you just dumped the air from the turbo to atmosphere ( ie: not even a downpipe) that the torque would not be good ?

Cheers,
Ray

ustolemyname??stevieturbo

iTrader: (1)

Out of curiosity...Has anyone actually measured EGP in the downpipe to see if the system is restrictive??
I also find it hard to believe that the different 3" systems etc would actually make a noticeable difference in power between them. Most appear very similar, with only minor bends, which are very smooth, and should not restrict flow in any way. The pic of the Pat exhaust has a minor bend before the back box, but it is a cut and welded bend. No matter how straight it looks, surely that joint at an angle would be worse than a smooth 3" mandrel bend ( very slight mandrel bend ) ??

David_Wallis

A decent tig weld shouldnt be a problem... and I heard that pat's system had been flow tested and I wouldnt dare comment without permission..

David

nom

Don't think he'd mind
No backpressure registered at all on the JanSpeed flow test thingy. It didn't even recognise it was there

LimeyDrink

John Banks - I noticed in a earlier post that you said "No one has gone over 400 BHP with UK heads", and you thought that maybe it was the cams/heads of your car that could possibly be restricting power.

Are there any differences between 95WRX non STI(AndyF), STI, and UK heads/cams cos Andy has over 400bhp, or has he changed things.

Cheers

nom

I think John's just trying to find an excuse not to but some more headers

LimeyDrink

There seems to be a bit of debate of how effective headers can be as some people have not been that impressed. I think the benefits you're gonna get are related to the state of tune you are at, as you go to various stages of tune different components start to become a restriction, I would personally have thought a car producing 320WHP could benefit significantly by the addition of some decent headers(assuming all other breathing mods have been done) considering the state of the standard ones although I could be wrong as I am no expert, just going on the fact that I've seen standard next to HKS and the former looked awfull with much less cross sectioanl area to flow.

I have HKS headers and noticed they have a sweet spot around 4000rpm, I noticed a difference straight away and I was still running the standard up-pipe, I then removed this along with porting the turbo to match the up-pipe removing the horrible step where the turbo mated to the up-pipe and I noticed the felt like it was breathing much freer.

ustolemyname??stevieturbo

iTrader: (1)

I still find it strange that a post ( by a Rigoli )ages ago I read on the US Subaru forum, said that the Rigolis still used std manifolds on their cars, and they do go quite well.

MrContro

I'm surprised at that Stevie, if they do then fair play to them, maybe they have them gas flowed or something and ported etc. ?

I always got the impretion that in NA engines things like headers can make quite a big improvement on top end performance and that this type of NA tuning can be even more effective to turbo cars due to the larger gas volumes involved.

I may be wrong and I'm not disputing that the Rigolis use stock headers but I would've thought you would want the freeist flowing exhaust system as possible which the stock headers definitely don't look as though they are... especially when you are talking about the kind of power they are producing.

cheers

Tim W

iTrader: (1)

Just for a comparison, have a look at what the HKS Hiper system that I removed looks like:



Notice how on the Pat spec exhaust how much larger the rear silencer is, and how much straighter and larger diameter the centre section is (also the lack of an expansion/silencer chamber!)

From memory, Pat's Silencer is 24 inches long, the HKS about 16...hopefully I'll get more flow and less noise...but a suitable noise still

john banks

Just changed from [Magnex twin dump DP down to 2.5" Magnex res centre to Blitz 3" BB] to [full Revolution 3"] and I got no extra power (320WHP) from doing so, and could not add any extra timing. However it is a heck of a lot quieter than the Blitz. I suppose I was trading a 2.5" centre with a very free backbox for a 3" centre and a quieter but still straight through (with resonator around it) backbox. The Blitz backbox does breathe very well, and the Revolution is a really nice volume. Quieter than full SS I would say. Removing the air filter (don't try this at home) also made no difference at all.

[Edited by john banks - 3/10/2003 10:30:48 AM]

john banks

I think I might just have to run more boost

What is the least boost anyone has used to break 400 BHP on a 2.0?

Headers are cheaper than head work anyway I suppose

[Edited by john banks - 3/10/2003 12:16:48 PM]

T-uk

planning on waking the dead are we tim?

looks impressive to say the least

[Edited by T-uk - 3/10/2003 8:21:04 PM]

Tim W

iTrader: (1)

Well, I heard (or not heard as it turned out) what it sounded like on Moray's car, and Pat is now running a version of it on his Legacy bus and it's not too bad, quieter than the Hiper I took off, but then again I did have the 2.5 inch taper on the downpipe...

It should be interesting to see how it behaves on my car with the HKS manifold

With this on the car I'm going to have to check the pipe everytime I start it up to make sure nothings tried nesting in the muffler

Oh and I should mention I can get my arm right up to the shoulder in the muffler

[Edited by Tim W - 3/10/2003 9:49:17 PM]

EMS

I donīt think there will be much of a difference in flow for the different heads available. The cams are different though, I donīt know what difference that could make in power. Someone made a direct comparisson between STi and non-STi cams?

(I will look in the new topic started for the STi cams)

Mark.

[Edited by EMS - 3/12/2003 12:13:05 PM]

T-uk

I think the main reason JB did not like the headers was that they highlighted the standard knock sensor glitch over 5000rpm. I actually think he wishes he still had the headers on the car, if he had known about the problem of the ecu not listening, even with standard headers he might not have been as quick to sell but he would have to confirm.

[Edited by T-uk - 3/12/2003 7:00:29 PM]