How to tell which cat is better??

[Sean]

I'm going to be removing the exhaust from my 325is here, and putting it on my Super Eta, so I don't have to buy a new one just yet.

My question is - both exhaust systems are the same, and I'm thinking that I want to try to choose which catalytic converter to use between the two.

Some notes about them:

I believe neither of them are rusted, so that is not a factor.

The Super Eta cat has 210,000 miles on it, and I don't know how long the engine was misfiring, but doesn't it have an affect on how clean the cat is?

The 325is has 181,000 miles, and I'm not sure what the cat has gone thru on that car.

As noted, both LOOK in perfect condition. But, I'm just want to make sure I use the best of the two of them. ;)

Note: Is it try that weight is a deciding factor? If so, I could weigh both to find out, but it would probably be seem marginal.


Or, am I just thinking and worrying about something that is not that big of a deal? :P

Thanks!

[KenC]

Which car has had a better running engine the longest?

A catalytic converter will never "run out" because it is a catalyst. However, your cat will eventually get 'clogged' up over time if your engine has been running rich.

When was the last time you went through DEQ inspection? (Do you even have those in Idaho?) If you don't need to pass any sort of inspection it doesn't really matter; you could probably go ahead and hollow it out for better performance (although you'd be shooting a ton more pollution into our air).

[Jand3rson]

Re: How to tell which cat is better??

Or, am I just thinking and worrying about something that is not that big of a deal? :P

Yes. It shouldn't really matter too much. There's hardly any difference in mileage on the two, and the only thing that fucks up a cat really bad is if the car is running rich. If the super-eta was not rich, then it should be fine.

Why are you switching them in the first place? They are the same.

[Sean]

Yeah - I figured it wouldn't make much of a difference.

I'm not quite positive how each car was running thruout it's life.

The only thing I know if that the Super Eta was misfiring for a month or two, as Kris was trying to get that fixed so he could pass emissions.

I'm basically only looking at this possibility because I want to get the muffler off the 325is and put it on the Super Eta, since my current muffler has rusted to pieces.

I think I'll just stick with my Super Eta cat then - it's less labor for now (won't need to remove the front part of the exhaust, just the cat-back.

Thanks, that's all I really needed to know! 8)