California carb Cat Converter needed 83 944

[Deacon Jones]

My car finally failed the smog test, reason is the cat converter. Unfortunately these suckers in California is trying to make thing harder with emissions to where they don't want us with older cars, and they're making it even harder in the upcoming year. Looking for a good used one, instead of paying a arm and a leg for a new one. Of course I'm in California

[Marine Blue]

Amazon sells a cat that works, I had to buy one because one of the previous owners hollowed out the catalytic. Make sure it includes the California carb compliant tag.

I would have preferred a used original as long as it came from a low mileage car but couldn’t find one at the time.

[curtisr]

I have one that I recently removed from an '87 924s with about 90k miles on it. This is from a track car and they must be removed. You can have it for the cost of shipping. I'm in Canada but it shouldn't be much.

[hejeva]

How much total?

[v2rocket_aka944]

All of the MFRs have online catalogs to look up CA-compliant cats.

MAgnaflow, Walker, etc.

I lived in CA with my 944 from 2005-2019 and used this cat without issue to pass CA smog in 3 different counties. Easy chop/weld job for an exhaust shop.

https://www.walkerexhaust.com/find-my-part/part-details.html?part_number=81101&brand_code=BDCN

[Monkey Wrench]

That was a generous offer Curtisr made.
Here in BC we had emissions testing, it was elliminated.
lots of theives were stealing them. If emissions testing isn't a thing in a certain area then Id have no issue putting in a bypass pipe or knocking the guts out. If it is you may need one. I think with the newer cars they will go into error mode. I do not think the thing will influence on how well the 944 runs, unless it gets plugged up.

[Marine Blue]

I have the Magnaflow version in mine and it literally registered zero emissions when I had it tested. I will also say that the car runs better with the catalytic installed, much better torque across the entire RPM range.

[Monkey Wrench]

changing exhaust system parts might change flow or backpressure, but other than that I dpn't understand how it would affect the engine performance. By the time the exhaust reaches the cat, its alrady past the 02 sensor.

the cat burns off unburned fuel basically so it probably heats thre exhaust through this reaction, the heated gases would ten expand and increase in volume parhaps theat could increase backpressure ?

could the performance increase be because the car had too little backpressure ? maybe that affects things like the way the exhaust is tuned to the engine.
in a lot of cars with performance mods it is thoughthat a larger exhaust increases HP. by inceasing flow
does it or does it just make more noise and give one the feelign of more power?

I can see reason for the design change ( increasing ehhaust diameter etc) if you are porting and polishing and increasing turbo boost or cam changes, or cylinder dispolacement because then one has increased backpressure by moving more air. there is probably a point where backpressure is inhibiting power.

i guess youd need ot do dyno tests to prove or disprove some of this stuff. or maybe race and use track times as a means of measure.

[Marine Blue]

^^Agreed. Porsche does a pretty good job of designing parts around the engine to maximize power within the constraints of fuel economy and octane availability. Bigger won’t be better unless you address the tune and other limitations either upstream or down.

In my case the additional back pressure helped, the car definitely runs better.