Crumbling Catalytic Converter

[preston_brown]

Just thought some might like to see what the inside of a 20 year old catalytic converter looks like. This is from my '87 Carrera. Based on the condition of the nuts/bolts, I don't think it has ever been off.



As you can see the ceramic matrix that does all the work is broken and crumbling. However, I have never had a problem passing emissions here in NC, even with the CO and related checks, but I doubt the cat was helping too much. I am replacing this with a Fabspeed pre-muffler now.

Complete thread on my engine re-seal project here:

Woo Woo! Engine out

[Emission]

Mine looked much the same - but also melted from the intense heat from the turbo!

I bought a new one so I could pass smog.

[88911coupe]

What in an emmission test would indicate a bad/failing cat? I recently failed my test here in Dallas and then passed with new plugs and a bottle of techron but I think my '88 also has the original cat. Any obvious signals of a failing cat?
Thanks

[stormcrow]

Save that old cat and knock the innards out. It makes a difference in performance if you can pas emissions without a cat.

Steve

"A Porsche does more then just go fast in a straight line"

[squidmarks]

I was thinking about getting a test pipe to replace my cat (my '82 doesn't need smog in MA). Is it easy to just "knock the innards" out of my existing cat?

Geoff

[Rick V]

You can gut a cat quick but you will end up with a rattly sound. I recomend replacing the cat with a new one from Pelican, like mine

[Cooper911SC]

Buck- if your Cat. is failing both the CO and HC's will read high. If you lean or richen the mixture to try to correct for this it will further make either the CO's or HC's higher and you will fail.

It is easy to knock out the innards of the Cat. I used a long (18") flat blade screw driver and a ball peen hammer. As I broke away the pieces I used a shop vac. to suck them out. The larger pieces just kind of suctioned onto the hose and I pulled them out. I did mine with the Cat on the car. My innards looked like Emission's except way more melted. I replaced mine at around 230,000 miles.

(While the muffler if off and after the Cat. is punched out, I HIGHLY recommend starting the car up! Sounds BAD ASS!) I ran mine around the neighborhood for a half hour.

[88911coupe]

Cooper, thanks for the reply. My recent emission test took two tries to pass on the HC's. I passed by ONE POINT the second time. Just curious though...if you rip out the cat innards doesn't that hurt your chances of passing emissions? I have heard that 3.2's do run pretty clean if all's correct.
BTW, Rick you cat has good taste. My Corgis are way to fat to fit in a box.

[Cooper911SC]

Buck- I gutted my Cat. and ran it that way for a couple of years until I had to smog my car again. You are right, you likely wont pass without the Cat. The one I gutted was the original and had been rattling inside from the deterioration of the core.

I replaced it, leaned the mixture slightly, and passed smog without any problem.

Oddly enough, I am due for a smog sometime before the 22nd of this month. I'll see if the after market Cat. I installed 2 years ago is still working.

[Oliver Klosov]

If you don't have to submit to any emission tests, can you replace the cat with a straight pipe? Will this increase HP? If your engine is properly tuned, will it vastly increase emmisions?

[Cooper911SC]

Oliver- Yes you can replace the Cat. with either a Euro "Resonator" (Pre-muffler), or a straight pipe. Bursch and other companies make them. The HP gain is very minor.

The best thing you can do with the stock SC exhaust system is to replace (back date) it with the older 70's equal length headers and a dual inlet muffler. Many here have written about back dating exhaust systems. Do a search. The HP gains are like +12 to 15

Cheers, Cooper

[DB_NC_95C2]

Fabspeed pre-muffler is a nice piece, I took that route with a Dansk sport 1-1 as soon as my county ditched the pre-OBD II sniff test, I didn't EVEN want to see what my cat looked like, I just wanted it GONE. Of course then I decided I needed to wake my SC up even more, so SSI heat exchangers and 2-1 M&K. HUGE difference. Absolutely love the sound (and I know 2-2 M&K might net me a touch more power and way more sound, but I wanted to keep the stock look).

[Jesse16]

Same year Carrera, 87, no issues with smog testing here so out goes the Cat and I'll budget either the bypass or pre-muffler. Likely the pre-muffler as I don't want excessive sound. Mine is melted/gone for 1/2 of the depth by my measurement. This thing must have been restricting the flow ?
Poor/fuzzy photo, I also have difficulties taking close-ups.

[craigturbo02]

Took all my Cats out huge difference before removal car was asthmatic , pass's MOT every time (find yourself a nice inspector). Must admit our laws are different over here cats only count from 1992 on wards.