the cat scenario
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From: Poway, CA
the cat scenario
ok, so i've been having ideas rolling around in my head about putting some exhaust in my 90 f150 with the 300. but i just can't seem to come to a conclusion as to what to do with those catalytic converters. (does anyone really know why 2 was so necessary?). i know i could mod the exhaust alll iwant, but that the real power will come from ditching those things. so, my question is, what have you guys done about the cats? keep in mind, this is a CA truck still in CA so it'll have to be smogged every once in a while.
here's one idea i had, but i don't know if it's quite rational. Unbolt the exhaust at the collector and then cut the pipe after the cats. then just lay in some new pipe and all i would have to do would be to weld the cats back in every now and then. would something like that work, or am i missing something?
here's one idea i had, but i don't know if it's quite rational. Unbolt the exhaust at the collector and then cut the pipe after the cats. then just lay in some new pipe and all i would have to do would be to weld the cats back in every now and then. would something like that work, or am i missing something?
Senior User
Joined: Feb 2000
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From: Connecticut
the cat scenario
Not sure about the 300 6 but for my 89 5.0 there are companies that make single free flowing converter kits. Mine bolts up the the header/manifold. I believe it is a Walker, can't remember for sure. 2 1/2" outlet. Not to much diff. in performance though.
Mark
mjb1962(No Email Addresses In Posts!)
Mark
mjb1962(No Email Addresses In Posts!)
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the cat scenario
When messing around with the cat's there are a few guidlines that you must do. If you want to swap them for high performance cats made for that model you can only legaly do it if your cats have 50,000 miles, 5 years, or have failed (i.e. smog check). I know someone that removed his from his chevy completely and it made a huge difference in his sound but he would have to put it on again for smog checks. But if you do remove it completely just don't forget to put them back before smog checks.
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the cat scenario
Hi, the easiest thing to do it pull them down and gut them then reinstall them and nobody knows the difference just drive a pipe through them the front one is the tough one but can be done by cutting the pipegutting it and putting on a coupler I did this to an 84 with a 5.0 as long as it was tuned up it went right thru smog tests and if they looked for cat they were there.
John
John
Laughing Gas
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From: Banning CA
the cat scenario
Fatforty you are wrong, here in Calif we have to go through smog checks on a dyno every other year. It will show up on the test. It is also illegal. Keep in mind that Calif has the strickest smog laws around. And the test is no different
Dave
http://a2ztowing.homestead.com/a2ztowing.html
Dave
http://a2ztowing.homestead.com/a2ztowing.html
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the cat scenario
First of all you guys must realize that todays emissions tests WILL DETECT THE ABSENCE OF CATALYTIC CONVERTERS!!!!!! Even if you take them off and knock of the guts, the test will detect this! There is no way of getting around it. Even here in good old New Mexico they have implemented these testing devices. If you don't have your cats on you car when you test, you will get nailed for this! Don't do it! To help you guys out and stay legal you can buy high flow catalytic converters that will clean the exhaust without robbing horsepower. Trust me they exist and they do work. I installed a 3" high flow cat on my 300 and the exhaust is super clean and damn near no backpressure!!!
To address your problem whiteboyslo, as stated in post #2 you can remove your cats if they have 50,000 miles or 5 years on them. However replace these two cats with a single 3way+air high flow cat. Summitracing sells them. Good luck bud!
To address your problem whiteboyslo, as stated in post #2 you can remove your cats if they have 50,000 miles or 5 years on them. However replace these two cats with a single 3way+air high flow cat. Summitracing sells them. Good luck bud!
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Laughing Gas
Joined: Jun 1999
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From: Banning CA
the cat scenario
Just keep in mind that the farther back the converter is from the engine, the less effective it will be. Since it requires high heat, to start the buring of the unburned fuels. This is ther reason ford uses two cats up front and a third on some of there vehicles.
Dave
http://a2ztowing.homestead.com/a2ztowing.html
Dave
http://a2ztowing.homestead.com/a2ztowing.html
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the cat scenario
and fox body 5.0 mustangs have 4 cats, and the thing about replacing it with a single cat? Not in california, it is illegal to tamper with the original placement of the cats, meaning no you cant put dual pipes with one cat on each pipe, might be cleaner but its not the way it was from the factory...if you really dont want them just buy an offroad pipe setup that is pre-bent and has no cats but is meant to bolt up to the exhaust manifolds, that way you can bolt your original exhaust back on every 2 years and not have to worry about it.
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Posting Guru
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From: Poway, CA
the cat scenario
Very cool guys. very cool. I like the idea of putting one 3 inch cat in, but is it CA smog legal? (does it come with a carb #) but the idea of putting in the off road exhaust and swapping when it comes time to get smogged is enticing, too. where would i find an exhaust setup like this on a strict budget? Thanks again.
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Joined: Nov 1999
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the cat scenario
Yeah, I agree, good sugestions all.
I've found a shop here in Houston that is all over these high flow cats and say will pass any emission test. I haven't checked to see if they have an EO number, as that hasn't been required yet, only a yearly tailpipe test.
BUT:
Houston is the EPA's #1 non-attainment area, and there are all sorts of draconian emissions-related rule proposals out there, and I just betcha an EO number is among them.
Since I'm custom-connecting a six-cylinder dual-outlet headers to an existing 3" cat-back, I think I'll find a dual-inlet/single 3-in. outlet high flow cat with an EO number and have that cat flanged to both catback and connector pipes so I can unbolt them easily and bolt the stocker back in if I have to.
I've found a shop here in Houston that is all over these high flow cats and say will pass any emission test. I haven't checked to see if they have an EO number, as that hasn't been required yet, only a yearly tailpipe test.
BUT:
Houston is the EPA's #1 non-attainment area, and there are all sorts of draconian emissions-related rule proposals out there, and I just betcha an EO number is among them.
Since I'm custom-connecting a six-cylinder dual-outlet headers to an existing 3" cat-back, I think I'll find a dual-inlet/single 3-in. outlet high flow cat with an EO number and have that cat flanged to both catback and connector pipes so I can unbolt them easily and bolt the stocker back in if I have to.
Senior User
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the cat scenario
You could always do what I did, but then again I live here in la manana New Mexico and I can get away with it. Basically CPs dual outlets headers into a Flowmaster Y-Pipe into a 3" single in/out hf cat. My exhaust was so clean that I surprised the hell out of the emissions tester! He kinda looked at me funny like he didn't believe what he saw. DUH!! Its called modifying an engine you quack!
Freshman User
Joined: Jan 2001
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From: Canada
the cat scenario
I got rid of the dual cats on my 89 F250 4X4 5l. I went with a 3" flowmaster exhaust from part of the y pipe to the back. I went with 1 high flow cat which has lower levels of emissions than the year before I did the exhaust.In the lower mainland of B.C Canada we have to get the older vehicles tested once per year, and the newer ones every 2 years.We also have some shops up here that will make you a pipe to bolt in so you don't have to run cats, then when you are going to get tested you can just remove the pipe & bolt in the cats.
Hope this helps Rich.
Hope this helps Rich.
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From: Keweenaw Bay, MI
the cat scenario
Amen, I did the same thing with a 351W, I took a long chisel and knocked out the inside and re-installed it. Worked like a champ. I got about 3-4 mpg better mileage and much better acceleration.
Laughing Gas
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From: Banning CA
the cat scenario
ALL of you guys need to know about California Smog laws before giving out this advise. In California, they will fail if it first does not pass a visual inspection. Meaning that if the cats are changed or not as they were from the factory it will not pass. Regardless of how clean the emission is. Yes stupid but that is Calif law.
California also has rolling checkpoints, they will randomly inspect vehicles to test exhaust. I have seen this many times, and if they find you have tampered with the cats expect a fine. CHP along with BAR stands for Bueral of automitve repair, and South coast air quality are the ones doing these randon tests.
Dave
http://a2ztowing.homestead.com/a2ztowing.html
California also has rolling checkpoints, they will randomly inspect vehicles to test exhaust. I have seen this many times, and if they find you have tampered with the cats expect a fine. CHP along with BAR stands for Bueral of automitve repair, and South coast air quality are the ones doing these randon tests.
Dave
http://a2ztowing.homestead.com/a2ztowing.html