well ive heard that removing it will add horse power to a turboed engine due to less back pressure. how much louder would the car be, would you be able to smell it really bad(ive heard it stinks bad when you take it out), and where would i get a straight pipe to replace it with.

 

It can add HP to ANY engine, doesnt have to be force fed.

It might stink after you take it out, most likely like a rich/raw fuel smell.

Any exhaust shop will have pipe to replace it with.

 

oh, so it would stop stinking after a while?
are o2 sensors a problem? if not then how would i pass emissions

 

Moving... Keep stuff in its related forum....

 

The purpose of the cat is to reduce the emissions of things like unburned hydrocarbons (gasoline). Without the cat, its going to smell rich. It isn't going to change over time... the engine will be pouring out unburned HC's, CO and NOx. That's why the cat is there in the first place.

With regard to the O2 sensors, you have to at least tell us the details of the car - year, model, engine. Without that, no one knows how many O2 sensors it has, whether it has post-cat sensors, etc.

Ditto with "pass emissions".... what emissions do you have to meet? What state? What kind of test? Is there a visual examination for cats? Is there a tailpipe test. Or is it just to plug into the ALDL connector?

The HP gains from removing the cat on modern engines is so small that its really a waste of time. But then... depends on whether you have a stock engine, highly modified engine, stock exhaust, dual exhaust, etc.

Tell us about your car and the emissions requirements, and people can give you accurate answers.

 

well my dad took the cat out of his car and i dont think it smells any diff... he has a neon srt-4

 

I removed the cat on my turbo z-28 after I eventually nuked it, and if you breathe the exhaust fumes it feels like it's going to kill you... it's Very potent. It's a convertible and I don't ever smell the fumes while driving it though.

I think it's possible to pass emissions w/o a cat if tuned properly (strictly to pass the sniffer test. If you have downstream o2's (OBDII), the computer will know you've removed the cat and not allow you to pass emissions, you'd need an o2 simulator or reinstall a cat for the test.

 

It pretty easy to spot the cars with missing cats, just driving behind them. The smell is obvious. Takes me back to the 50's when there were no cats, cars got 9 MPG and they all smelled of raw fuel.

Cat is probably going to make more of a difference on a turbo, than on a "stockish" engine.

 

i guess ive just never walked behind his car and smell the exhuasted gases then haha