[Persian Whisperjet]

Originally Posted by BB_cuda

I had the same question about whether or not he used 300 series wire. I don't have the needed tri gas either but do have 308SS wire.
Hey at least the welding will be on the top side where no one can see it. If you used normal steel filler wire, make sure to put some high temp paint on it to keep from rusting.

You guys are way ahead of me. I'll check.

[TDIwyse]

Originally Posted by BB_cuda

...

Back to my question related to 2 way versus 3 way cat discussion now started. I had found the 200 cell with heavier reactants in it versus normal 200 cell hi flow, if you recall. I had wondered if the $30 was worth it in terms of better scrubbing. Prior to reading above, I had presumed the comparison i was trying to do was same catalytic process but more of it. Another layer of the onion to peel off now .......

Found some data/analysis that might be of interest to others.

This first one compares several different types and cell densities and loading weights and goes over performance tradeoffs. It's really a nice analysis, although its on a gasoline engined vehicle.

http://www.emitec.com/fileadmin/user..._SAE_Paper.pdf

This discusses some higher level stuff and comments about the typical cpsi for diesel catalysts being in the ~300-400 cpsi range.

https://www.dieselnet.com/tech/cat_substrate.php

Think I'd be leaning toward going with a ~200 cpsi metal mesh heavy loaded cat.

If anyone has more experience with an aftermarket cat in the 335d exhaust I'd enjoy hearing more feedback. Especially interested in how the EGT's of the car affect the efficiency of the cat at removing odor. For instance with in town driving the EGT's can get well below 400F ... from graphs of conversion efficiency this seems like it would be too low to do much...

[DWR]

Originally Posted by TDIwyse

town driving the EGT's can get well below 400F ... from graphs of conversion efficiency this seems like it would be too low to do much...

Right on the money, in fact the same problem happens with gas cars. SI engines can actually run quite lean with modern ignitions. The problem becomes having enough "emissions" to keep the catalytic reaction going and the up to temperature. Its been that way for a long time and a pretty messed up situation if you ask me. Car needs to get worse mileage so it can run cleaner.

For a diesel very lean AFR is possible. Here's a presentation on the same issue with CI. https://www.erc.wisc.edu/documents/symp13-Durrett.pdf

[TDIwyse]

Fantastic link DWR. Thanks.

[Persian Whisperjet]

Check out the big brains on Brad everybody!

[fawndog]

I've found a easy way to fit a aftermarket 335i system to the 335d.
I bought a 335i exhaust system/ 2.5"-3.0" Y pipe/ 3.0" 2 bolt flange pipe.



Then we fitted the system under the car to measure where to cut the 3" flange pipe. It was really short and required a couple of angle pieces to be cut and fit.

[fawndog]

The Y pipe has a good length to slip fit over the dual 62mm pipes from the 335i system. We tacked the adapter together and bolted it to the DP.



Then you just fit into place, tack weld and remove the whole thing.



The cut off 335i length (the fitment length between the 335i/335d flanges is almost the same)



Angle



2/3 of system

[fawndog]

It is barely louder, but it has allowed me to keep the stock unit intact for emissions. The car does seem peppier, but we still have a DPF in place. The potential of the exhaust won't be enjoyed until the DP/DME switch.

[shnaggs]

Wow, this is cool! may need to do this...

[sukutash]

Originally Posted by BB_cuda

Cat is likey more effective in removing stink the closer to engine it is. My thought is perhaps more direct than others. What if a high flow single cat where down stream of the downpipe/mid pipe junction. I'm talking further upstream than where SCR currently resides. My thought was to do a singular 3" all the way back. It would look dumb to only have one tip coming out of the diffuser. If downpipe is 3", wouldnt continuing with 3" all the way back be fine. If not, perhaps a 3.5" or 4" single. Maybe I would go get a 328 m sport rear panel and be in cognito. I know I'm way out of bounds of the main stream single to dual split method

I'd be interested in a single 3" all the way back. I guess we're the minority.

[BB_cuda]

fawndog, I used a very similar Y pipe as well. It was front end of the same circuit werks kit too. My Y was put in a little further aft though. I have about a 8" section of 3" pipe before the Y though. I got my Y from Columbia River Mandrel Bending for $80 as well.

sukutash, I went for the duals after all. It was the cheapest way to get the exhaust. I worked out a deal with the vendor to not buy the back muffler pieces as they had found someone else that wanted the back pieces only. They sort of played match maker. I had a local custom shop do back pieces for me.

[Whitbread]

Originally Posted by sukutash

I'd be interested in a single 3" all the way back. I guess we're the minority.

I held a single 3" pipe up there when I did my car and the problem is the single 3" hangs way down low going around the rear end and in general through the tunnel. Anyone with a lowered car would have a hard time getting in and out of some curbed areas. Also, two 2.5" tubes are going to have a larger cross sectional area than a single 3".

[shnaggs]

Whitebread, you don't have any of those collectors you had made left, do you?

[Whitbread]

Originally Posted by shnaggs

Whitebread, you don't have any of those collectors you had made left, do you?

I have 2 left. I had them custom made by Columbia River bending to match the same centerline as the chinesium exhaust where I wanted to cut it.

[shnaggs]

What do you want for one?

[DWR]

Originally Posted by Whitbread

I held a single 3" pipe up there when I did my car and the problem is the single 3" hangs way down low going around the rear end and in general through the tunnel. Anyone with a lowered car would have a hard time getting in and out of some curbed areas. Also, two 2.5" tubes are going to have a larger cross sectional area than a single 3".

Yep, two 2.5" tubes are more than big enough with a 3" single. 2.25" would also work just fine. If you have TDIwyse power levels a 3.5" single would be better with the 2.5"duals, for a no power loss system. Of course, 3.5" is also a tight squeeze

[GreekboyD]

First 4 seconds gives you an idea of the sound at idle before revving. Crank up the volume.

Taken in the summer.

Cold start up in the winter sounds even meaner:

[BEWWWM]

profi diesel out of bulgaria just made a turbo back system for me, will be here next week.

[fawndog]

Quick clip.