Exhaust Question

[mikelv]

My question involves exhaust components.

The car in question is a 2G GST.

I have a T4 setup. T4 Tubular Manifold, and T4 Turbo. 46mm WG is flanged off the manifold. The turbine has a 5 bolt outlet. I could not find anyone who makes an O2 housing flanged for this type of turbo on a mitsubishi. So what I did is essentially custom weld a downpipe with the 5 bolt flange (a flang from Forced Performance) all the way to the cat-back exhaust. Then welded a bung on the pipe for the O2 sensor.

My question: It is okay to run this way. What are the pros and cons of not having an O2 housing. Should I make an O2 housing, and weld the flange on here?

 

[Zack Huffman]

Not necessary. As long as you have a bung for the O2 you're golden. Nobody makes a Garrett turbine outlet flanged O2 housing, as far as I know.

 

[Nors]

If I am reading this right, you pretty much did a 02 elimination exhuast. Which RRE and some other companies sell, I have never heard of problems with these, but I also new to DSMs so hopefully someone with some expierence will chime in.

 

[mikelv]

Thanks for the replies guys.
Well the issue I'm having, I think I was off on the fitment. I'm getting moderate vibration in the exhaust. Now, there is a horrible exhaust leak somewhere that has led me to have a concern for what I did.
I was able to get under the car and check it out today. It seems nothing is visible as far as broken or cracked. I say this because I had a problem before of the flange bolts actually rattlin' loose and the downpipe actually disconnecting from the cat.
I've also had other problems of bolts coming loose. A manifold/turbo bolt actually rattled loose prior.
I'm wondering if my measurements were off enough, or if engine vibration is cause enough stress to make this happen. Or maybe not having the proper locking washers, ect...
Also, I do not have enough experience with flex sections, but I felt around, and it seems something is rattlin' or "loose" inside so-to-speak the flex section of downpipe. The exhaust leak is quite loud, as though its coming right from the manifold, or right off the block. It was a sound comparable to the one I had in which one of my manifold bolts rattled loose.
Would a broken flex section make a seriously loud and noticable exhaust leak? The car bogs like hell too now.
I've inspected all aspects of the pipe and manifold for cracks as well. Nothing noticable. Minor cracks maybe? I wouldnt think it would be so loud.... it sounded like there was no exhaust at all. Thanks guys!

 

[Talesin]

Yes, a broken/dead flex section will make for a VERY loud exhaust. It's like running open DP, but worse. Improper torquing will let the bolts/nuts back out through normal engine vibration.

If your muffler is small enough, I'd just take a rag or something and partly/completely plug the end. If it makes a noticeable difference in the idle/kills the engine (not sure how safe this is, really) then there's a good likelihood that there's no leak, and the exhaust is just loud. If it runs perfect with the muffler completely plugged, the exhaust is getting out somewhere else. Check your welded section for cracking, then pull the DP off and have a look. Should only be four bolts and a hanger to drop it, after removing your O2 sensor, after all.

 

[mikelv]

Thanks guys, I will make sure to give reps points where credit is due

I'm going to be taking off the DP today and welding in a new flex section and see if this is the problem. I was worried it was something worse such as the manifold cracking.

Ill let you know whats up.