Porting turbo's exhaust housing?

[BPaulsen]

Just received a 16cm exhaust housing for my turbo, switching from the original 21cm.

Looking at the size of the exhaust gasket (the part that sits between the exit of the exhaust manifold and the turbo charger's exhaust housing), and comparing it to the size of the exhaust housing's port, I see a big difference. It would be possible for me to take out chunks of metal from the intake of the exhaust housing, using a Dremmel tool, but I was wondering if there's any merit to doing so. Maybe it would be a waste of time?



#ad

 

[dpuckett]

Draw a line on the housing flange a hair (1/16-1/8") smaller than the gasket line and leave the manifold alone. Then blend the grinding into the housing. It works better if you have a 1/4" shaft die grinder, as you can reach in farther than with a Dremmel, though I have ported a few housings and manifolds with a Dremmel. If done right, there is a lot to be gained. You'll have the flow of a 16, and the spool of a 14 or 12.



There is a thread that I thought used to be part of the stickies "How to Port and polish" or something to that effect. I followed the instructions in it to port my housings, and I have done half a dozen or so.



Daniel

 

[sdstriper]

Port matching is what your after, the exhaust is just slamming into that wall there the way I see it.

 

[PToombs]

I never thought to do that to mine. I always miss the obvious stuff. I did use a die grinder and smooth out the walls as far down in as I could reach.

Oh well, I better go pull the turbo again, glad I put a zipper on it! :-laf

 

[Bob4x4]

Be prepared to spend some QUALITY time with a dremel :-laf Even with a good air die grinder you will spend a bit of time.



Bob

 

[Forrest Nearing]

you don't want a step where the manifold meets the turbo, but I seriously doubt you'll gain anything from porting the turbo out to the gasket as the manifold outlet is still going to be a lot smaller than the gasket orifices

 

[Greenleaf]

What Forrest said. I enlarged the manifold flange and then did the same to the turbo. Cut both. However, I was told by an employee at PDR that cutting it the way I have will slow the travel of air due to the enlargement. The only thing you want to do is smooth the castings not hog them out.



I'm not sure as to where the air will hit a wall. Like Forrest said, The manifold flange is much smaller than the gasket just like the turbo flange.



I cannot say if I found any benefits.

 

[JLEONARD]

Well I say grind out the turbo to match the gasket, then smooth it off the best you can inside. The air will still funnel down inside the turbo and you won't lose velocity. You will gain overall as there won't be a "wall" for the air flow to get interrupted by.

 

[sdstriper]

Too quick assuming the ports didn't match, my little pee brain saw that gasket and port "wall" and makes me think the manifold and turbine housing are not port matched at all...



I would "match" ports or at least make sure there is no "wall", don't know if I would spend a ton of time matching that gasket unless I had a really good die grinder and cutters. You'll be full of chips and metal slivers before you know it...

 

[Forrest Nearing]

porting the turbine housing larger than the manifold will help prevent reversion... you don't want it to be outrageously larger, but a little larger isn't a bad thing by any means

 

[JLEONARD]

will help prevent reversion

Yes, that's what I meant by my so many words.

 

[Sri Ram]

BPaulsen, yours is a new housing, right? I was surprised at the amount of dust when porting my 18cm. Mine was used and all manner of nasty exhaust residue filled the air. I used a respirator and goggles. But, I should have had a full mask, like you use for painting. That's my 2 cents; and I say go ahead and port it!

 

[TWorline]

I ported & smoothed mine all the way down to the bend, it had a bad parting line that ran down that far into the casting, guess they don't pay the casting finishers for doing to much. Be carefull up on the flange as the casting can get thin quick where the ports exit the flange.