I recently had to do a smog check, and after bringing it to shop and failing the first time, I started looking around at what to do. I have a RX-7 store DP, Random Technologies HF cat, and a cat back. It is also a very large street port. I brought it to a friends shop, and the guy said that all i have to do it replace my cat and i should be fine. I spent over $600 two years ago and now its already broken? The guy said that since the engines get so hot, the mess up the Cat. Is this true, or did he just want some money for the illegal smog?

 

it should still be fine unless your running to rich.

 

I have been told by a reputable tuner that a lot of brand new high flow cats wouln't even pass emissions testing. CA I imagine is pretty tough do you still have your stock cat? I would just swap it back in and do the test.

 

the bonez highflow cat work very good. I pass california smog with room to spair. if your car is working properly you shoulg get years out of a cat. running to rich without an air pump or air control valve will kill the cat quick.

Jeff

 

I'll second the above, I passed CA smog with a bonez cat. I can't tell you too much about its longevity but it's rumored to be good. However, I'd be pretty concerned about your large street port, that might make passing difficult to impossible regardless of what cat you have.

 

It depends on a lot factors - one of which is tuning.

It is hard to pass w/o trick when you have a street ported motor.

 

most aftermarket HF cats use a ceramic core, which after a while melts by the high rotary exhaust heat and eventually form a wall that'll block ur exaust flow. when you start smelling rotten eggs.. that's when ur ceramic HF cat is going out..

aftermarket ceramic cats usually last roughly around 2 years, which is one of the reasons why people switch over to Metal substrate cats such as SMB and Knightsports. I may be a bit off, but if i remember correctly, metal substrate cats last about 6-7 years.

 

+1. I think I've heard that before about the ceramic cats not being able to stand up to the heat a rotary produces.

 

did you have your airpump hooked up?

 

The evidence I have seen suggests just the opposite. The high heat generated by the rotary engines tends to melt the metal cats very quickly. A good quality ceramic cat (like bonez) should last a long time.

To the original poster: It may be that there is nothing wrong with your cat. Is it a metal cat? If so, it may be melted. If it smells bad, that is probably the case. Replace it with a stock cat for the test, then reinstall it if it doesn't stink too bad.

 

Why do you think his cat is fine?

 

agreed, if its metal with such high exhaust temp its gonna fail fast.