Using precats as main cats?
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,469
Likes: 6
From: Winchester Ontario
Using precats as main cats?
Hi, my exhaust system is Hooker 2149 long tubes, true 2.5" duals all the way back with a cross over pipe to 2 chamber 40 series Flowmasters.
Emissions time is approaching. I am scrambling to save every penny I got, cuz I got to put a new clutch in the car and they don't give them away for free.
I was wondering that since I'll need 2 cats to pass, if I could use the 2 precats off the stock exhaust system in order to save money and not have to buy 2 new cats? THey would just be put on for testing and removed after emissions test. How much would the 2 precats work and could it be done?
Emissions time is approaching. I am scrambling to save every penny I got, cuz I got to put a new clutch in the car and they don't give them away for free.
I was wondering that since I'll need 2 cats to pass, if I could use the 2 precats off the stock exhaust system in order to save money and not have to buy 2 new cats? THey would just be put on for testing and removed after emissions test. How much would the 2 precats work and could it be done?
Burning Brakes
Joined: May 2000
Posts: 1,160
Likes: 10
From: Nashville TN
Re: Using precats as main cats? (black_89_vette)
If all you do is an idle test, then I'm sure it would pass. But a roller test, I don't know, I'd say it would fail but I'm not poitive. I passed my LT1 with no cats on an idle test. However, a roller test made me fail misserably with 1 cat installed.
Are the pre-cats actual cats or is there something different about them?
Are the pre-cats actual cats or is there something different about them?
Advanced
Joined: Mar 2004
Posts: 57
Likes: 0
From: Elk Grove Ca
Re: Using precats as main cats? (black_89_vette)
Most emissions testing has two parts, there is the visual and tailpipe test. To pass the visual, the cats must be the original configuration. Therefore, if the car came with two cats, then you have to have two cats, it it came with two pre-cats and one main cat then it has to have the three cats.
When you say pre-cats, what exactly do you mean?? Pre-cats are simply small cats that are used before a larger cat. Pre-cats are not designed to be primary cats in a large displacement engine like a 5.7.
I know this might sound confusing, but the bottomline is you need to get the cats back into the original configuration. A good honest muffler shop should be able to help you.
When you say pre-cats, what exactly do you mean?? Pre-cats are simply small cats that are used before a larger cat. Pre-cats are not designed to be primary cats in a large displacement engine like a 5.7.
I know this might sound confusing, but the bottomline is you need to get the cats back into the original configuration. A good honest muffler shop should be able to help you.
Team Owner
Joined: Sep 2002
Posts: 22,209
Likes: 12
From: OBAMA IS HITLER
Re: Using precats as main cats? (TimBVette)
Most emissions testing has two parts, there is the visual and tailpipe test. To pass the visual, the cats must be the original configuration. Therefore, if the car came with two cats, then you have to have two cats, it it came with two pre-cats and one main cat then it has to have the three cats.
I know this might sound confusing, but the bottomline is you need to get the cats back into the original configuration. A good honest muffler shop should be able to help you.
I know this might sound confusing, but the bottomline is you need to get the cats back into the original configuration. A good honest muffler shop should be able to help you.
I got two universal 9" body Magnaflow cats, had the exits pipes cut on each and had them welded into my Hooker 16720 Y pipe. They fit just right. There's no way around this, in my case I would have been limited to 4,999 miles annually. No way! This isn't ideal in a performance setup, but I also have another plan that will take care of that (you can read between the lines :D )
Instructor
Joined: Dec 1999
Posts: 132
Likes: 0
Re: Using precats as main cats? (black_89_vette)
Hi Black_89_Vette
I'm from Ontario (Oakville). I had to pass Drive Clean last year with my 1990 L98 Coupe and I just had a Walker 3 way cat and no pre cats. My Precats got plugged and when Holland Chev_Olds in Burlington changed the front y-pipe they offered me the Front Y-pipe with the main Cat attached for $499.00 + GST/PST. It was a much better deal than the abortion setup GM had with those damn precats (replacement original equipment 2 x precats and 1 main cat was about $1750 with the taxes-a total ripoff.
As it was, with this three way cat, I passed the Drive Clean, but my NO ppm was 746 and the pass was 750. My CO% was 0.00 vs 0.37 limit and the HC ppm, was 16 reading vs 67 limit. I don't know of the precats would be enough, as GM put them on there to help emissions during warmup.
Maybe you would have nothing to loose, and if you fail, then a high flow cat would be the way you would have to go. I have heard that Drive Clean may be scrapped by Ont Govt, so many Drive Clean places are not really making money. Sounds like a good idea, to go along with the scrapping of those turkey Conservatives that brought it in along with the 407 fiasco. Sorry for rambling.
Regards,
Dan
I'm from Ontario (Oakville). I had to pass Drive Clean last year with my 1990 L98 Coupe and I just had a Walker 3 way cat and no pre cats. My Precats got plugged and when Holland Chev_Olds in Burlington changed the front y-pipe they offered me the Front Y-pipe with the main Cat attached for $499.00 + GST/PST. It was a much better deal than the abortion setup GM had with those damn precats (replacement original equipment 2 x precats and 1 main cat was about $1750 with the taxes-a total ripoff.
As it was, with this three way cat, I passed the Drive Clean, but my NO ppm was 746 and the pass was 750. My CO% was 0.00 vs 0.37 limit and the HC ppm, was 16 reading vs 67 limit. I don't know of the precats would be enough, as GM put them on there to help emissions during warmup.
Maybe you would have nothing to loose, and if you fail, then a high flow cat would be the way you would have to go. I have heard that Drive Clean may be scrapped by Ont Govt, so many Drive Clean places are not really making money. Sounds like a good idea, to go along with the scrapping of those turkey Conservatives that brought it in along with the 407 fiasco. Sorry for rambling.
Regards,
Dan
