[TDIwyse]

A little more progress on this and some pics that may be interesting to others.

First off, there was a lot of water inside the OEM muffler. After a quick web search I found other bmw owners reporting similar things. Here's an example from a gas bmw:

http://www.e90post.com/forums/showthread.php?t=198349

When I first cut it off I noticed some liquid come out as I was dragging it around. Wiped up the liquid with a rag and smelled it. It was not diesel. The shop I used to cut and bypass the muffler told me that after they had it clamped into place to start working on it, that after a couple minutes there was a lot of liquid that started to drain out. He thought it was diesel. But if that was the case I'd expect the packing material to smell like diesel. It doesn't. So I'm certain it was water from condensation that soaked the packing material through the perforations in the pipe inside the muffler chambers. It's been a super cold winter, and with the mods I'm running the EGT's are much lower than they were pre DPF/SCR/EGR delete so evaporation from the packing material was more than likely impossible.

So, the original weight of ~40 lbs included probably 1-2 pounds of water.

Instead of the BMW clamps, I found some 60mm Audi clamps online that were much cheaper.

I had bought some straight 60mm stainless pipe off Amazon as well to bypass the muffler section.

Re-used the rear most hanger from the OEM muffler, and the input and output/tips of the OEM pipe.

I like the sound with this configuration, as well as the weight savings. Think I'm going to get it hard welded into place in the next week or so.

[JDG]

Nice progress, I hope to get some Cyba tips and have a shop just weld them on and remove the muffler sections. If the DPF pipe ever comes out, I may just straight shot it with some mufflers in there to make it civil.

[Puerto Rican 335d]

TDi wtf no baffles just a cannister damn Im surprised on this

[TDIwyse]

Me too. Unless the other side has something different (I didn't cut that one).

[Puerto Rican 335d]

wow I am amazed at this, so we really dont need those cannisters for nothing as i see it

[dzlmoose]

TDI any chance you could post a sound clip of the exhaust?

[TDIwyse]

Originally Posted by dzlmoose

TDI any chance you could post a sound clip of the exhaust?

Will try to get that done this weekend. I've tried to capture some clips twice now, but the wind really messes with the sound.

[TDIwyse]

Well, the wind is from a direction that my house/trees block it. The car is inside the garage but the rear is close to the outdoors.

Not the best quality, but for a quick and dirty shot it gives an idea of what it sounds like.

I did notice there's more turbo whistle coming through on the video than I notice with my ears in real life. I don't hear any whistle inside the car with the windows up driving.

When doing a heavy acceleration on the road there's more growl than what shows up in the video with the engine reving without a load.


http://www.youtube.com/watch?v=gTGuJe4nCrg

[JDG]

the link doesn't work. Can you tell use exactly what your mods are? I want the growl and some whistle but very little cabin noise. Sounds like you nailed the sound Im looking for.

[FormerRotor]

Originally Posted by TDIwyse

...
I like how things sound with the present configuration, so I'm not going to fuss around with the resonators after all. The 2.5" Vibrant Ultra Quiet resonators weight about 6 lbs each on my scale, so they would be ~12 lbs + some pipe to bridge the distance, so probably ~16-17 lbs when its all done. Would still save about 22-23 lbs over OEM. But just having straight pipe (I've got 5 ft of 60mm stainless here) should only be ~6-7 lbs. So that would be a 33-34 lb savings.

...

Ok, definitely doing that now, although I wish it were off the front of the car.

[TDIwyse]

Originally Posted by JDG

the link doesn't work. Can you tell use exactly what your mods are? I want the growl and some whistle but very little cabin noise. Sounds like you nailed the sound Im looking for.

Is anyone else having an issue with the link? I have it set as "unlisted", but if you have the link I show above you should be able to view it. Please let me know if it's not working.

[JDG]

well worked on my tablet but not my pc. Sounds pretty good

[TDIwyse]

Originally Posted by JDG

well worked on my tablet but not my pc. Sounds pretty good

I changed the link awhile ago. Hadn't logged out and saved the final state of the video. That's probably what the main issue was...

For the simplicity, ease, cost and weight savings, it seems like a decent alternative to a fancy custom exhaust.

Guess I'll end up selling the ultra quiet resonators and perhaps the entire SCR exhaust section as well.

[JDG]

works well now. I like the sound. Also your underside looks very clean

[TDIwyse]

Originally Posted by JDG

...Also your underside looks very clean

Ha! Probably because those big arse muffler sections were blocking all the dirt, mud, snow, sand and salt ...

[TDIwyse]

Wasn't happy with the huge volume of non-aero left over space after the removal of the mufflers. So I fashioned a functional rear diffuser to help reduce the turbulence and smooth the airflow. Initial testing seems good. Planning to do some more trimming of excess material and possibly spray paint the non-painted portions.

[Puerto Rican 335d]

TDi it sounds nice I like it

[TDIwyse]

Got it trimmed up and did some further testing. Comes in at just over 5 lbs which eats a little into the ~34 lb saving from the muffler delete. Total cost is about $150.

Started with one of these:

http://www.ebay.com/itm/Universal-Re...b2e5c6&vxp=mtr

Took off the two middle fins and put them on the outside rear of the car behind the wheels and aimed them similar to the VRS example described in this fantastic thread: http://www.e90post.com/forums/showthread.php?t=856744

Then used 2 of these to cover the remaining air gaps on the left/right edges.

http://www.lowes.com/pd_241560-37672...063&facetInfo=

Then there was also lots of fussing around with test fitting, drilling, experimenting, etc. But so far I'm quite happy with it.

[335dFan]

Originally Posted by TDIwyse

But so far I'm quite happy with it.

OK, dumb guy question (note: I am the dumb guy). What sort of handling or other change might one notice, even if very slight, on the track for example from doing what you have shown here? I mean the recent diffuser work. Thanks in advance.

[FormerRotor]

Pretty sweet TDIwyse. Why do I feel like with your need for data you will be renting a wind tunnel in the near future

...or at least a really big fan and a smoke pen

[TDIwyse]

FormerRotor ... if only I had access to a wind tunnel! I'd like to get myself and my triathlon bike in one as well.

335dFan:
Not a dumb question at all. I didn't know much about this either until after I removed the mufflers and was just looking at that huge, open, volume of space left behind right in front of the now parachute like bumper, and thinking through the turbulence issues that it was going to cause. Also noticed some difference in handling at interstate speeds with the mufflers out, especially in windy conditions. And the EGT's seemed a bit higher than I was used to seeing for similar conditions...

Here's a quick overview: http://en.wikipedia.org/wiki/Diffuser_(automotive)

And here's a guy on e90post who put together a fantastic thread on his DIY aero work (way, way, WAY beyond what I'm willing to do for a daily driver) that's filled with fantastic data demonstrating huge gains in his intended application: http://www.e90post.com/forums/showth...ar+aero+sensor

It seems that the EGT's with the diffuser in place are lower. But until I do a back to back test I'm not going to claim any advantage on any aspect with it in place.

[TDIwyse]

Originally Posted by TDIwyse

That's an excellent question, and I haven't addressed it yet. I was going to add some distilled water into the active/passive tanks and let that slosh around and then drain again. ...

BB_cuda, the unending winter has started relenting. Added as much distilled water as would fit (got 4.5 gallons in), drove around for couple days, then drained it all back out. The fluid coming out no longer smelled of urea and no crystallization of the draining liquid was evident. Put on >3k miles since the previous draining.