Ok....just thinking back to when I did my P20 upgrade, I was thinking of porting the entry to the P20 but found that the my stock up-pipe diameter was smaller than the P20's entry. From memory the stock up pipe was 45mm internal diameter while the P20's entry was 54mm so basically as you can see there was nothing really to port....this is on an 06 XT so maybe the STi's up pipe is bigger. What was your up pipe internal diameter, standard?

Also have you investigated the effects/negative-effects of the way you have ported the inside of your P20?....I have seen it done before but all the way round the casting rather than only one side....I can understand why you did it as per your photo but I'm wondering whether you'll get any strange things going on as the exiting exhaust gases will be more resticted on one side of the turbine wheel than the other.

I also ported the wastegate hole and opend up the size a little too, to prevent any boost creep at high boost.

iv ported the wastegate too, no pics of it.

The up-pipe diameters would be the same, to port - is not to increase the diameter of the pipes, rarther - get rid of the flange/gasket restriction. The flange still protrudes out from the gasket - so what happens is that exhaust flow hits this and creates a restrication as it has to be forced into the main path again.
Porting gets rid if the protruding flange from the gasket, hence forces uniform distribution(wel as much as) travelling from one pipe to another.

I will post a pic of the previous FP Green I ported when i get home, i did this all the way around, as much as i could get it even. But speaking to Norm Butler when i picked up the dump - and telling him about what i was gonna do - it seemed better to port more one side than the other - as the splitter does not go all the way into the turbo - therefore the idea was that porting the other side more would help the "splitter" effect.
cant hurt no matter how 'ugly' it looks

Yeah, I understand the theory behind porting....what i'm trying to get at is, if the up-pipe diameter is smaller than the the P20's entry then there is no flow restriction...there was no real gasket restriction as it lined up pretty much with the P20 entry.

porting is one thing, port matching is where the modifications are effective

__________________

Long live the WRC

take a photo with the oem gasket on

__________________
MY93 Impreza GX 1.8L, 0hp, 0nm

In my case it was, as the FP green had a larger inlet than the stock up-pipe. So I ported it to utilize the bigger opening. So the stock p20 housing was smaller already because of this.

The inlet to the turbine housing is between 0.100" and 0.125" smaller than the outlet of the stock headers (..on the radius, about a 1/4" on the diameter).

I wouldnt bother porting if the pipes matched.

Take a look at this way:
In my case u have to look at it from the begining... when i ported my headers, and changed to a 44mm cross-pipe - the opening of the headers where smaller than the block. So porting here was essential. This point here created more flow to the turbo.

Getting rid of the 32mm restriction in the middle to a 44mm x-pipe:
area = (pi)(radius)² = (pi)(diameter)²/4 = 0.78539 (diameter)²
a = (0.78539)(44mm)²
a = (0.78539)(1936mm)
= 1520.5 millimeters squared - for larger opening in headers

compared to 32mm crosspipe restictoin:
a = (0.78539)(32mm)²
a = (0.78539)(1024mm)
= 804.24 millimeters squared for crosspipe

(804.2) / (1520.5) = 52.9% reduction in airflow (very roughly!)

take away 15% losses and shit + or - on top (thermo/turbulence/cast iron resitance etc etc)

u can see how much damage it does even if this quick calc is just a rough guestimate based on the pipe mm opening. And yes its about port matching as stacey said.

Heres a website which pretty much confirms what tode is saying

http://www.gnttype.org/techarea/turbo/turboport.html

Mostly cause he copy & pasted directly from it. I didn't realise you were driving a Turbo Buick Regal

__________________
MY93 Impreza GX 1.8L, 0hp, 0nm

yep, which i got off nasioc

but it the same principle as the pipe is the same same

Ah NASIOC, good choice of information.

__________________
MY93 Impreza GX 1.8L, 0hp, 0nm

Not really as this reference (Also a copy paste you have made) points out.

http://www.isiaz.com/turbochargerrestrictors/

What they are refering to is intake restriction not exhaust gas flow.

Your amazing 44mm cross pipe (why would it be 12mm larger in diametre then that standard piping??) does not ADD flow what so ever. All it does it balance the gases. Some people believe this to be a pointless.

If your going to pass something off as your own at least use it in the correct context.

__________________
[DBR]