Real cats definitely make a difference...

[nrubenstein]

Before:
HC: 1.214 (2.000) - Pass
CO: 10.8167 (30.0000) - Pass
NOx: 3.4704 (3.0000) - FAIL

After:
HC: 0.0605 (2.000) - Pass
CO: 0.9735 (30.0000) - Pass
NOx: 0.0158 (3.0000) - Pass

Magnaflow spun metallic vs. BMW OBDII. Quite a large change on all fronts, even the ones that notionally passed the first time around.

[MC Hammered]

Can you post up a pic of where you put the OEM cats in an e30 exhaust setup?

[pandaboo911]

did you run 2 magnaflow cats or 1?

[nrubenstein]

did you run 2 magnaflow cats or 1?

The original exhaust was the traditional 3" single swap exhaust. So, one Magnaflow 54959.

Currently, I have a modified E36 M3 exhaust on there with the cats located at the front of the stock heatshield. (Same as with the old exhaust.). This was a real hacked together job that I constructed to get he car to pass. I'll be changing it up a bit, although I am enjoying the peace and quiet that I get from the E36 muffler.

[MC Hammered]

I was hoping you came up with a permanent install using OEM cats and I need them to pass too, however, I can't figure out where to place them as there is just not a lot of room to work with under there.

Only real option is to replace the midsection I have with some cats.

[nrubenstein]

I was hoping you came up with a permanent install using OEM cats and I need them to pass too, however, I can't figure out where to place them as there is just not a lot of room to work with under there.

Only real option is to replace the midsection I have with some cats.

From the cats back is basically permanent. Forward of the cats, I halfassed things together so that I could pass emissions and pull the engine. The problem right now is not the cat placement. It's that the forward pipes were slapped together without worrying about whether or not they would make slight contact since I'm redoing it all.

[nrubenstein]

To be clear, to make it all fit, you need to do the following:

1). Cut out basically all of the pipe forward of the cats and remake from scratch.
2). Section out a few inches of muffler piping.
3). Cut off the outside (left) seam on the muffler and then weld it closed. You need this half inch.

[MC Hammered]

So you took the OEM OBD2 cats from an e36 and were able to spice them in?

If you have a picture you can provide me of you cat location it would help me out as I can't imagine it with my cold remedy fogged brain.

[wazzu70]

Great info on how much difference "real" cats make!

[nrubenstein]

So you took the OEM OBD2 cats from an e36 and were able to spice them in?

If you have a picture you can provide me of you cat location it would help me out as I can't imagine it with my cold remedy fogged brain.

Everything from the cats to the muffler is E36 M3. The cats are located in the stock E30 cat location.

I'll take pics when I have it up on the lift tomorrow. You'll also have a chance to laugh at how halfassed I made the front section. :). It's really bad.

[nrubenstein]

Here is where the cats sit:



Here is the muffler connection:



And here is the really sloppy connection to the manifolds:



All of this wants some refinement, but the point was to get it in as quickly as possible for reworking later.

Sent from my iPad using Tapatalk HD

[MC Hammered]

Thanks for the pics as it helps me plan what to do with my setup.

Looks like I will be replacing the RD midsection I have this Spring.

[nrubenstein]

Thanks for the pics as it helps me plan what to do with my setup.

Looks like I will be replacing the RD midsection I have this Spring.

If you have eyeball arms, you only need to rework to get the height fixed. All that effort was necessary to get around stock lollipops.