n8kruger

All
I'm looking for options and if anybody has experience with similar issues. The car is a 1986 Carrera that is mostly stock with 117k miles. It runs well, doesn't smoke and hasn't been rebuilt.

Two or three years ago the exhaust crossover pipe broke at the flange. Since the heat exchanger needed to be removed anyways, I fell prey to the "while you are in there"disease. In Connecticut the car no longer has admissions requirements and I replaced the catalytic converter with an M and K pre-muffler with a new oxygen sensor and a sport muffler.

The sound is barely noticeably different from stock. The performance increase is modest at best. The problem is without the catalytic converter, the aroma of unburnt hydrocarbons is enough to give the car and the garage that old car smell. My wife and kids complain. Perhaps enough to decrease the overall enjoyment of the car. "Daddy's loud car"has become "daddy's stinky car."

I'm sure I can put the old catalytic converter back on but after more than 100,000 miles, should I just replace it? Pelican sells an aftermarket cat, but it doesn't look like stock and the review says it won't fit the heat shield. Are there high-performance catalytic converter's available?

r911

I'd check to see if anyone makes a dual cat system for these cars.

or maybe a retune can bring up the WAF (Wife Acceptance Factor)

n8kruger

Does anyone have experience with a Dansk 100 cell cat?

Techno Duck

Check PartsGeek.Com for the DEC branded cat, its cheaper than what Pelican has it listed for. I have this one and ill say its not pretty, but it has the magic stamp on it that makes it legal for use in California.

I recently bought this one from FabSpeed. They just had a 10% discount last month through Rennlist, send them an email and see if they will still honor it.. i was a few days late and they were nice enough to do it for me . My car stinks pretty badly also, it has a M&K euro pre-muffler that ill be replacing,

http://www.fabspeed.com/911-carrera-...tic-converter/

https://rennlist.com/forums/vendor-a...-products.html

ron mcatee

The euro premufflers are not CAT's. They are just a premuffler. I would have the adjustments checked to ensure they are correct.

CT Mike

Does everyone agree that the odor may be caused by not having a catalytic converter?

n8kruger

The smell wasn't there before the catalytic converter came off. I'm aware that at some point the valve guides may need to be done but replacing the cat seems much more appealing and less expensive.

Spyerx

My 3.2 is substantially less stinky w/o cat after I had the afr adjusted... It was running a bit rich.

CT Mike

I wonder if a cat delete Steve Wong chip would make a difference?

Chris M.

Euro Carrera here, Euro pre-muffler, ie no cat. Mine says "that car smells like a chainsaw."

Adams

Very curious about the opinions on this thread. I'm contemplating the move to either pre-muffler or high flow cat, hoping for pros and cons here. I'd not even considered the 'smelly' factor if I go pre-muffler.

As a possible suggestion to the OP, I bought the 02 wideband gauge to set it accurately, perhaps that helps mitigate the stinkiness?

fastdiablo

n8kruger, what did you decide? did you replace the stock cat? did it need it? i'm also wondering if it's better to just replace it at 100K miles.
also, did you say the M&K was barely louder than stock? i was thinking about keeping the stock CAT and doing the M&K 1in 1 out or the Fabspeed Supercup. not sure how big a diff the muffler makes if you keep the stock cat.

n8kruger

Fastdiablo
The M and K pre-muffler and my Dansk replacement muffler are minimally louder than stock. There's a slight low frequency resonance around idle speed but I can't tell the difference driving. The sound and performance difference are similarly underwhelming.

Unfortunately, otherwise I won't be of much help. I chose option E, none of the above. My dad (who bought the car with me in 1991) agreed to put the car in his garage for the winter at least. This way, the minivan goes back in our garage and my wife stops complaining. No need to do anything else for the moment. I'll let you know what happens in the spring time.

Chris M.

I've had many combinations of 3.0/3.2 exhaust from stock to straight pipes. Keep in mind all exhausts are subjective; one person's perfection is another person's deafening.

A stock muffler with a cat bypass is barely louder than with the cat but there is a deeper tone. It smells horrible.

A stock cat and no muffler (using the Fabspeed muffler bypass) sounds great with lots of pops and burbles on the over run but is fairly loud. It's cheap though and if you don't like the sound you can easily sell the bypass.

A cat bypass and no muffler is extremely loud, as in race car loud, ie essentially straight pipes, and smells horrible. You can be heard half a mile away. NOT recommended for a street car and not very efficient hp-wise for a race car.

A Euro pre-muffler with a stock muffler has a deeper tone than a stock car but also smells bad.

I also had pre-74 heat exchangers (SSIs essentially) with megaphones which sound great for a race car but you wouldn't want that for street. I had that as well with M&K race mufflers instead of the megaphones and it was the loudest most obnoxious exhaust I've ever had. People on the track behind me would complain about how loud it was, at a RACE.

n8kruger

Chris
Thanks, everything you said makes sense to me. I was hoping that someone had experience with any of the high flow/200 or so cell cats. Is that enough to make the unburnt hydrocarbon smell go away?
Best,
nk