Running Without A Cat? Or Both Of Them?

S

Street Wolf

Guest
What would be the issue running with one of the cats, or perhaps both of them removed? I can think of a couple advantages right off the top of my head, but was just wondering what issues it may cause.
 

R_Lefebvre

Expedition Leader
What advantages?

First of all, you'll have the CEL light on permanently. Secondly, you'll be polluting for no real good reason. Thirdly, your exhaust will stink, bad. You'll make life miserable for anybody stuck near you in traffic, and you'll even notice yourself if the wind is blowing from behind. Lastly, it's quite illegal and subject to hefty fines if you get caught, and given how much it smells, that's likely.

If you're thinking about performance increases... extremely minor, unless your cat is actually failed. I ran catless with my trackday car for a few years, then I got sick of the smell, and put a high flow cat on. I'm making 250hp from a 2.0L, so hard to say that it's really hurting performance.
 
S

Street Wolf

Guest
What advantages?

First of all, you'll have the CEL light on permanently. Secondly, you'll be polluting for no real good reason. Thirdly, your exhaust will stink, bad. You'll make life miserable for anybody stuck near you in traffic, and you'll even notice yourself if the wind is blowing from behind. Lastly, it's quite illegal and subject to hefty fines if you get caught, and given how much it smells, that's likely.

If you're thinking about performance increases... extremely minor, unless your cat is actually failed. I ran catless with my trackday car for a few years, then I got sick of the smell, and put a high flow cat on. I'm making 250hp from a 2.0L, so hard to say that it's really hurting performance.



Well I've got one cat removed as of right now due to it being bad and not having a replacement currently. No check engine light either, which is odd even in my opinion.

One advantage I can see, other than letting the engine breath easier, is the cat on the passenger side that is right next to the driveshaft trying to toast the thing which even Tom Woods notices at a problem.

I've run catless on my car for quite some time now since it's running a blower and nitrous and the cat was making a very noticeable restriction. Which is aside the point but there is a definite gain to be had with the POS's gone.
 

SeaRubi

Explorer
i ran high flow cats from summit racing on my RRC. worked great and picked up a few HP to boot. a local exhaust shop welded them in for me.

the only downfall is that they were big enough that i wouldn't have been able to run a beefier drive shaft. I used a DII shaft and clearance was tight. just have it rebuilt with serviceable ujoints (you want that anyway) and you should be fine.

fwiw

cheers
-ike
 

R_Lefebvre

Expedition Leader
Well I've got one cat removed as of right now due to it being bad and not having a replacement currently. No check engine light either, which is odd even in my opinion.

One advantage I can see, other than letting the engine breath easier, is the cat on the passenger side that is right next to the driveshaft trying to toast the thing which even Tom Woods notices at a problem.

I've run catless on my car for quite some time now since it's running a blower and nitrous and the cat was making a very noticeable restriction. Which is aside the point but there is a definite gain to be had with the POS's gone.

So, what exactly were you wanting to find out with this thread?
 

Chazz Layne

Administrator
Well I've got one cat removed as of right now due to it being bad and not having a replacement currently. No check engine light either, which is odd even in my opinion.

That is odd, though I could see it taking a while before the computer catches on to the change.

You have the 4.6, right? My understanding is that there really isn't much that can be done to improve the airflow through these engines beyond where they already are, besides a new filter/snorkel and cutting off the resonator. In fact, less heat on the driveshaft is probably the only significant benefit you would get. That could also be accomplished by simply installing a smaller aftermarket cat (easily cutting the size in half) and wrapping the exhaust in one of the many heat shield products on the market. Then you wouldn't have to worry about the fact that FEDGOD is watching either. :D
 

FlexdXJ

Adventurer
I've run catless on my car for quite some time now since it's running a blower and nitrous and the cat was making a very noticeable restriction.

You don't really believe that hype do you?

It doesn't matter on your drag car but on your rig you need to have a cat on it. They act as a spark arrestor, Prevent excess pollution, and on top of all that they are federally Mandated and required by law on any street driven vehicle.
 

ntsqd

Heretic Car Camper
This document applies specifically to engine swaps, but note the wording of the first paragraph:
http://www.epa.gov/compliance/resources/policies/civil/caa/mobile/engswitch.pdf

Then there's this:
http://www.txdps.state.tx.us/vi/Misc/faq/engine.html
The simple rule is that a vehicle must have all emissions components that were present when it was manufactured,
and:
http://info.sos.state.tx.us/pls/pub/readtac$ext.TacPage?sl=R&app=9&p_dir=&p_rloc=&p_tloc=&p_ploc=&pg=1&p_tac=&ti=30&pt=1&ch=114&rl=20

Which starts off with this:
(a) Any person owning or operating any motor vehicle or motor vehicle engine on which is installed or incorporated a system or device used to control emissions from the motor vehicle in compliance with federal motor vehicle rules shall maintain the system or device in good operable condition and shall use it at all times that the motor vehicle or motor vehicle engine is operated.

All of this from less than a 20 second search.
 

JSBriggs

Adventurer
You should be OK if you only have two O2 sensors. If you have four, one up stream and one down stream of the cats on each side, they you will throw a code.

-Jeff
 

stolenheron

Explorer
mouse.jpg
 

rugbier

Adventurer
Not entrirely correct.

I used to own a 355GTS ( Euro Version ) 1995, brought into USA through a well known Prancing Horse Florida Dealer.

I had no AirBags and no Cats, and was legally Titled and Registered, and quite honest, I am not sure what are you talking about smell, as it was a GTS ( Targa ) and run all year round without the top.

SOLD and registered in VA

Then after that one, a 360 Challenge ( Euro Version ) again, no cats, straight capristo pipes and racing exhaust, same legal deal and smell statement.

I knowwwwwwwwwww, you are going to flame me for no reason.
 

R_Lefebvre

Expedition Leader
Maybe the smell has more to do with incomplete combustion than just the fact there are no cats. All I know for sure is that being around Detroit for 6 years, I was around a LOT of old muscle cars, and they smell. And my trackday car smelled, but it had a racing ECU and big 42lb injectors and the AFR was never at 14.7. After I put the high flow cat on, and tried to keep it closer to 14.7 so I could pass emissions, it doesn't smell anymore. Could be your Ferraris ran cleaner since they were probably OEM engine management. Could also be your own personal sensitivity to it. People tollerate all kinds of things for their cars, not just smells. Happens all the time. "What's with that?" "What? Oh that (insert, smell/noise/vibration, etc)? That's nothing."

As for the legality... I don't know all the ins and outs of US law, as it regards those imports. But the law is very clear for vehicles originally sold in the USA.
 
S

Street Wolf

Guest
Maybe the smell has more to do with incomplete combustion than just the fact there are no cats. All I know for sure is that being around Detroit for 6 years, I was around a LOT of old muscle cars, and they smell. And my trackday car smelled, but it had a racing ECU and big 42lb injectors and the AFR was never at 14.7. After I put the high flow cat on, and tried to keep it closer to 14.7 so I could pass emissions, it doesn't smell anymore. Could be your Ferraris ran cleaner since they were probably OEM engine management. Could also be your own personal sensitivity to it. People tollerate all kinds of things for their cars, not just smells. Happens all the time. "What's with that?" "What? Oh that (insert, smell/noise/vibration, etc)? That's nothing."

As for the legality... I don't know all the ins and outs of US law, as it regards those imports. But the law is very clear for vehicles originally sold in the USA.


My car, which use to be my daily driver has 1 3/4" headers, and 3" inch pipe to the mufflers, nothing along the way. Paired with an aftermarket PCM and 65lb. injectors, with the A/C system removed so I had to drive with the windows down and sunroof up all the time, and I was never bothered by the smell.

Then again, this is aside the point and not what I made this thread for. I made this thread to find out what I codes I would have to overcome and any other issues to be able to run without the cats. However, now that I've been driving with the one bad cat removed since Monday morning, and still not throwing any SES light, it makes me wonder.
 

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