I think the catalytic converter my '90 s5 has is almost toasted.
Consequently it won't pass emissions.
I've already done everything else to it for emissions except replace the converter. To register it i can either spend $670 to fix it with 'certified repairs' to get a waiver or move.
The second generation rx-7s are supposed to have 3 converters; 2 little ones and a big one.
The car only has one now and runs fine.
If i put 3 converters on it like it is supposed to have, how bad will that hurt its speed?

 

You don't need the precats to pass emissions, their for cold startup only. Just replace the main cat and as long as everything else is running fine you should pass.

 

well i replaced the main cat so now i have only one than i got my gas tank to about 1/4 tank than i poured in 1 gallon of denatured alchol and passed amazingly

 

i tried every trick in the book, but what ended up working wasn't the cheap way. i just replaced the old cat with a new one and the numbers on the emissions test were way under the limits. sometimes my wallet hates me

 

lol i love south carolina no cats for me ..but yea just replace the main cat you should pass

 

Sometimes passing smog depends on where you go. Some shops will make it pass smog then gladly earn your money. While other shops will want you to buy something then charge to make it pass smog. Don't know if that is your case but It must happen often.

 

S4 NA's had 2 precats and one main cat, while s5 NA's only had one precat and one main cat. I would not even worry with the precats. Just buy a cheap cat and have it installed, pass the test, then unbolt it and put your old one back on. Next time when the test comes around, bolt your "new" test cat back on. If you install a cheap one and run it long term, it will generally die from heat pretty quickly and you also lost your investment.

 

What is a cat that would last on the RX-7? I think in STS racing, high-flows are not allowed, so what kind of cat would be able hold up to the heat of an ECU-tuned stock NA engine?

 

^Don't worry about running a cat long term. Like it's been said, just get one that fits, put it on for the test + run the old one (you can gut it out too if you want) everywhere else.


If you did for some reason want to run it all the time, the stock replacement is either 1600 or 400 at mazdatrix.

 

I can't race without a cat. It's against the rules in my class.

 

Oh. Ouch... Does it have to be a working cat? Shove the old stock one in there?

 

It can't be gutted if that's what you're asking.