Stupid question?

[Greyg]

I've talked to guys (who wish to remain anonymous) that have removed their catalytic converter and gotten huge gains in FE. I'm told this is illegal (which I figured it would be) but is easy to get away with in areas where there are no emissions tests to pass. None of the mechanics/technicians I work with are willing to do this, so I'm assuming it's very illegal. What are the pro's and cons to something like this? How big are the fines? How come I've never heard of this before? Cripes, I'm 40, I didn't think I was that uninformed.

[Jay2TheRescue]

I think if you are getting great gains from removing the cat then it was probably bad and needed to be replaced anyway. Removing it is highly illegal, even in areas that do not do emissions testing.

[theholycow]

In old (25+ years old) cars, the cat might not flow freely -- and might be rusted/worn to uselessness now anyway. Modern cats flow as well as the rest of the exhaust system.

[VetteOwner]

Originally Posted by theholycow

In old (25+ years old) cars, the cat might not flow freely -- and might be rusted/worn to uselessness now anyway. Modern cats flow as well as the rest of the exhaust system.

ya main reason wny my chevettes has gone "missing". 28 years old figured it was plugged or somehitng goin on with it...

ye sit is illegal to remove/modify any emmissions part on a car besides replacing it. but i dunno if i really gained anythign from it... sounds like a small diesel engine while idiling now...

[Backtobasics]

I agree that the people who saw improvements removed a clogged catalytic converter. The new "monolith" style are very free flow, and are minimally restrictive.

[GasSavers_BEEF]

I have heard the gains with a normal (unclogged) cat are about 1-2mpg and the fine if a shop takes it off is $2500 for the shop. at least it is in virginia. lived there most of my life. not sure for an individual.

my info may be dated and may have changed but I don't think it is worth it.

[mini-e]

Catalytic converters cause very little loss in power or efficiency, searching around the internet a couple times for 2-3 hours i found 1-3% power gains with removal and that was way up in the powerband. Catalytic converters work very well- if you ever get behind a car that stinks it is likely the cat(s) are removed or non functional. i was behined a 2004-6 audi a4 yesterday that stunk, it was lowered and had a custom exhaust, so the guy was running catless and pig rich for that oh so important 2% (or what ever) gain at WOT. Get off a plane in Bangkok or Mexico City and gag. Exhaust coming out of non emission controlled cars and trucks is utterly foul. I grew up in L.A. in the early 60's 70's and the air was very, very, gross. Now it pretty good, considering... Catalytic converters are in use for very good reasons.

[R.I.D.E.]

$2500 for individuals, $5000 for shops.
regards
gary

[GasSavers_JoeBob]

Originally Posted by mini-e

Catalytic converters cause very little loss in power or efficiency, searching around the internet a couple times for 2-3 hours i found 1-3% power gains with removal and that was way up in the powerband. Catalytic converters work very well- ... I grew up in L.A. in the early 60's 70's and the air was very, very, gross. Now it pretty good, considering... Catalytic converters are in use for very good reasons.

Same here. The air in LA is better (far from perfect, though) than it was then, even with more than double the cars on the road. And many more miles travelled per car than back then. Be nice to other people, leave the cat in place (or replace it if it is bad).

I've tried removing a perfectly good cat once upon a time in the '80s...no difference in mileage...so it went right back on.

[Ford Man]

Years ago it wasn't illegal to remove the catalytic converter yourself, but I think shops could be charged as much as $25,000. (federal fine) if caught removing them for you. Back in the '70's I had removed them from a couple of the cars that I owned so I could use leaded gas without the worry of it stopping up the catalytic converter. I don't remember it ever doing anything drastic for FE though.

After doing a search on "catalytic converter removal laws" I found out that the clean air act of 1990 is when it became illegal to remove them. It is even illegal to replace a known good converter with any other converter high flow or not.