348 Smog Test Results (with and without cats)

Well here are my Smog test results for both without cats and with cats. You'll notice the test from 07/02/2004 was without cats and it failed. And you'll see the test dated today 10/08/2009 was with cats and it passed. I've been running her for the last 5 years without cats; while the sound, lower heat, and a bit more power have been nice, I've decided to leave the cats on. The extra head ache of looking for "special shops" to get inspected has not been fun. So here are the results: The mechanic that ran the test was surprised as to how low the emissions output was.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

cool comparison. thanks for posting.

 

good post, thanks for posting.

 

+1

 

+2

 

Your 2009 test (low rpm) would have failed in CA. Your HC is over 50 which is the limit. My car after all the famous gothspeed mods and ND chip is right at 50. It is interesting to see how far out of compliance our cars would be without those cats. Anyone running no cats in CA is warned. We aren't even close to compliance without cats.

We are still pursuing the limits of legal modifications to our engines. My hope is that we can maximize performance and still keep it legal, but it is a fine line. I quip that we are doing what the factory should have done to explore the limits of their engine, when they seemed to be distracted by the replacement, Luca's 355 baby.

 

The 2009 test is with 16 year old cats with 12,000 miles. I hope new high flow cats would perform a little better in terms of emissions.

 

This is interesting; I just had my car smogged yesterday and the 15MPH limit is 112 (measured 25) and the 25MPH limit is 86 (measured 24). This is HC(PPM), and I'm in a Smogcheck II zone which has the strictest limits. Are the limits different for each Smogcheck II zone in California, or have they raised the allowable limit?

 

By "special shops" I assume you mean a place where they "don't notice" the missing cats. Why not get them put back on when you have to get the smog check? It can't be that much work. Just the associated heat and extra fire hazard gives me cause for concern when using the cats. Of course there are still legal issues and environmental issues with not having them installed all the time but that's another kettle of fish.

 

I would be very surprised if anyone had any luck passing the test in Ca with no cats, visual inspection aside. Our cars do not do well without cats on the dyno, not enough heat is created to burn off the needed HC's.

 

I have to check my paperwork again and get back to you.