jturkel

i have read on a couple of forums that the metal substrates are more resistant to heat than that of ceramic. i do remember from my chemistry days that ceramic becomes more brittle as it is heated. also, if ceramic were better with regards to not failing, why are they generally cheaper? supposedly the metallic ones flow more too. is all this true?

just looking for some clarificaiton.

Eleventeen

Yes, I think the main advantage is the higher flow rate. If you look inside, it's basically some sort of corrugated foil (looks like the edges of a cardboard box). You can practically see right through the cat which is great for flow, but the material used is about the thickness of notebook paper. Mine didn't actually seem to "melt", but I think the heat softened it up enough for the exhaust pressure to try to push the core right through the output end of the cat. That corrugated metal compressed and choked off exhaust flow at the exit of both cats. Jerry posted some pictures up a couple of months ago; he had the same issue and his pictures looked identical to what the insides of my cats looked like.

Jerry's thread:

https://mbworld.org/forums/c32-amg-c55-amg-w203/249273-high-rpm-misfire-solved.html

jturkel

so in the ceramic cats, the foil is more resistant to heat and thus more durable to run out our car?

c32AMG-DTM

It's an interesting theory... logically, I'd say it makes sense - running higher boost and richer tunes vs. stock might very well be shortening the useful lives of the primary cats. A 178mm crank pullied car with a flat 12-12.5:1 AFR would make less power (probably significantly less), but might not suffer these same issues...

kindafast

I'm going to change my other cat today, it appears that it is also malfunctioning. I'm just going to replace both primaries with aftermarket ones. However I keep being warned that my CEL will come on. What is the optimal Cell count to use for this not to happen?

Thank you!

greasybenz

Didnt want to make a new thread so...

I want to order some catalytics for my C32 as ive been pushing it to the side for awhile. But id like to make 100% sure that i should get 2.5 pipes on the cats to replace the primary cats or are they a different size?

ohlord

the pipes.
And are you under 80k miles?Then you would still be under 8/80 warranty.