Hollowing out the catalytic converter on VX
 

I did search and this was asked once before, but I couldn't find an answer. What are the negative affects of gutting the internals of catalytic converter on VX except noise, smell, high NOX emissions? Are there any FE, O2 life, engine affects?
Also, how do check if cat is bad? The engine I swapped in my car has been sitting for 11 years, so I figured cat is rusted and clogged, but I haven't opened it up to look. Engine is running.
Thank you.

If you punch out the cat the exhaust will be much more "stinky" (a little unburned fuel will be present) also more carbon monoxide will be released out the tailpipe (not good- especially if you carry many long loads and have to drive with the back hatch open).

To test to see if the cat is plugged, watch a vacuum gauge as you rev the engine to 3K or so. Let the throttle snap closed, the vacuum will increase slowly if the cat is clogged. If everything is OK, the vacuum will build fast.

Don't gut it unless you are sure it's destroyed anyway.

Remember that stuff inside is quite a health hazard, seriously.
And it's possible to hurt FE and performance by gutting a cat in good condition due to gas flow changes (it becomes more turbulent in the empty canister)

$2500 fine for owner tampering. That's Federal law. Your state may vary.

Prove its bad first at least. You can have it rebuilt for a coupe hundred dollars or get a good used one.

regards
gary

just want to share this link https://www.ehow.com/how_5135432_tell...r-clogged.html on how to solve the issue if your catalytic converter is clogged..

I don't know why this hasn't been mentioned before, but we really should not be supporting violating federal emissions laws here... I recommend if your cat is plugged, replace it with a new one. You can probably get an aftermarket cat for under $100.

-Jay

i gutted mine out in 95' for better performance, so i thought, and on the freeway i felt my vx backfiring from time to time.

I tried removing the cat on my Chevette some years ago when I was trying to track down some problems with FE. Over several tanks, noticed no difference in performance or FE. Put it back on. Conclusion: A properly functioning cat has no deleterious effects on performance or FE. Better to use it, be in legal compliance, and pollute less.

most all cars pass emmissions tests without a cat since the late eighties. Big brother requires use to have a cat anyways and it will effectively clean-up the exhaust further.

The draw back to hollowing out the cat is if its found that you need one it will cost you dearly to replace.

It will change the dynamics of a factory tuned exhaust that may hurt economy

There is a remote possibility you could face a fine up to $10,000.00 & jail time.

The car did sound pretty cool running straight-piped, however. But the stern stares from several Sheriff's deputies convinced me that it was in my best interest to return the exhaust system to its original condition...

lol my chevettes has rusted off in several occasions and i must say straight piped does make it sound neat :p makes it sound like a rally car

mine currently has no cat and stock muffler. at idle it has a nice little diesel sound (its a gas engine) it can and does pop when engine braking sometimes or if i rev it.

heck if motorcyclist can get by on that stupid excuse by saying straight pipes make me more noticeable (dont need to notice you in my house a mile away from the highway) so i don't get hit I can use that same excuse with my tiny car that goes nowhere fast.:mad:

cops around me tend to like my car, one just laughed as i went buzzing by goin 85 in a 55:p

This is NOT true.

Yes they will, pass emissions yes, visual/physical inspection fails no cat. Fuel injection & obd 1 cars are very well managed by engine/emission controls. 1986-87 the new age of V6's & 4's multi over head cams as well as the push rod motors, body & port injection better best thing since sliced bread. American & japan

Is it pass emissions as in pass the minimum standard, or pass in the car's certified rating? Will the SULEV car still be SULEV without the cat, or does it drop to Bin II?

I would define "pass emissions" as meaning that you are allowed to continue driving the vehicle without changing or repairing it.

Just to answer the question; I found no ill affects when I gutted mine. It was so clogged that I couldn't see through it, and a new one for my car is around $250. It sounds better now (barely noticeably louder from the outside), and my mileage went up (of course, since it was clogged), and I have passed yearly emissions 3 years since then. I get about 5 more MPG than EPA says, when I drive normally, and a couple more when driving for FE. The MX-3 V6 burns clean, though. I don't know about other cars.

Some states actually measure what's coming out of the tail pipe though. Then it's a matter of the law requiring that the car meets it's Carb or Fed rating, or some minimum rating. A blanket statement of "pass emissions" may not apply in all areas.

I knew a guy who had the cat hollowed out on a Ranger here, and had no problem passing inspection.

I don't know what platinum is going for, but selling the old cat to a recycling shop will offset the cost of a new one.

"Pass emissions" is definitely dependent on jurisdiction. In RI, the car is put on a dyno and a sniffer is put in the tailpipe. Cars over 25 years old (my Buick) and trucks over 8,600 pounds (IIRC) are exempt.

in NC it is done county by county. the county I live in only requires the OBDII check which means you fail with a CEL code. older than 1996 and they don't care.

the county beside of mine has no emissions. their inspections run $9.10 where as mine is right around the $30 mark. they also have the worst schools around and little to no industry.

We have absolutely no inspections up in MN, ND, I drove around an Escort with one working brake (3 including the required E-Brake), I also drove a Beater buick with a total of 5 exterior working bulbs, 2 headlamps, 1 tail, 2 front blinkers.

But, of all the cars I've owned (16 or 17) the only one I removed the cat from was my '86 Lincoln, which couldn't go more than 80mph due to exhaust being so plugged, turned out the cat broke, and the chunks were perpendicular to the flow. Even my '83 carb'd tercel had a working (original?) catalytic converter and +240,000 miles, I was trouble shooting the rough idle one time, and the cat was working so hard it was GLOWING orange in daylight! '86 tercel had well over 300,000 with still functioning cat.