What kind of welding process and filler?

[RipperXX]

So I got to thinking, I have always been unimpressed with my external Tial MVS setup and tubular O2 housings ability to dump enough exhaust to atmosphere to stop my MHI Evo III 16g from creeping. And I think I know a reason why.

Just like people who know better, won't hollow out a working catalytic converter, because of the large chamber the exhaust expands into, slows down and then has to go back though the same size piping it came In through. Due to it actually hurting exhaust flow.

I think the same thing is happening with my turbo. I originally did port the passage when I removed the waste gate flapper and welded a plug where the WG flippers arm passes through. I opened ed it up may even 2-3mm over stock, thinking that would be plenty with it dumping to the atmosphere now.

We'll it still creeps. And I'm thinking it's because soon as exhaust comes through the passage, it's going into a larger chamber that was designed to feed into the Evo III o2 housing. But it's not.

Instead it's then going into a pipe, to the MVS Tial WG. I think that chamber is hurting flow, and prevent ting an adequate amount of exhaust to bypass the turbine.

Sooo, what I want to do, is either fill I that cavity, or preferably weld in a pipe that lines up well with the tubular o2 housing pipe to the WG.

What kind of materials would I need?
308SS? Pipe, what thickness? What filler rod? Definitely don't want something coming lose and clogging the passage at WOT.

TIG or stick?


EDIT:
NM I think I'll try to add material to the tubular O2 housing to close up that chamber portion of the turbine housings WG passage...and port it some more. Hope I'm not over thinking this.

 

[RipperXX]

So this morning I got up early and in a couple hours had the turbo off, O2 housing off the turbine housing and hmm well while my memory of that cavity was larger than it seems to be, and theoretically I suppose it is hurting flow, doesn't look like it could possibly be choking the flow enough to cause the creep. So I grabbed my caliber and got it in there as best I could. the WG passage, which I had already ported some, only appears to be about 29mm. Looks like if I open it up until that pipe like projection is removed (what the flapper used to seal against) then it should be about 33-34mm. Sooo I'm going to take it to work tomorrow and see if I can get the port opened up and see if that cures my 20-23.5psi boost creep problem when it's supposed to only be 14.5! (1 bar WG spring)

 

[donniekak]

I never understood the logic behind spending $100's to still end up using the stock wastegate passage. I know people will crawl out of the woodwork talking about how it's not optimal, but a 2g mani with a 38mm flange welded onto runner #1 let me run as little as 6 psi with a bunch of different turbos from a 14b all the way up to a hx40.

 

[RipperXX]

I never understood the logic behind spending $100's to still end up using the stock wastegate passage. I know people will crawl out of the woodwork talking about how it's not optimal, but a 2g mani with a 38mm flange welded onto runner #1 let me run as little as 6 psi with a bunch of different turbos from a 14b all the way up to a hx40.

Yeah, wish I had gone that route...now. Is there even a decent manifold out there with the option to mount a WG on it anymore?

 

[donniekak]

Yeah, wish I had gone that route...now. Is there even a decent manifold out there with the option to mount a WG on it anymore?

I don't there are any in production now. But like i said a 2g mani with a wastage flange welded to the #1 runner worked great for me for a long time.

 

[RipperXX]

Oh, you just modified a OEM manifold... I must have missed that. I have an Evo III exhaust manifold. If it comes to it (but it shouldn't.) I'll go that route.

 

[Justin Lauscher]

Do you have your turbo ported like so? I did this to mine and it enabled me to run as low as 7psi on my tdo5h 20g.

 

[RipperXX]

Do you have your turbo ported like so? I did this to mine and it enabled me to run as low as 7psi on my tdo5h 20g.

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That's it as of yesterday. Planning on reinstalling it today. Not sure if it needs more, but I think the volute is fine, I focused on the WG passage and massaging the volute on the WG side to make a smoother tradition into it.