I have a 94z, an was wondering has anyone ever removed their cat and experienced a loss in power? I had the cat removed and the car actually lost almost 3 tenths in the eighth mile. I then put the cat back on an immediately the car was running just like it always had. If you have removed the cat what kind of exhaust setup were you running afterwards, did you see any improvements in your times, or is exhaust tone the only noticable difference?


Thanks in advance

 

in my '93 I got faster and gained power on the dyno after gutting the cat. I don't have 02 sims or anything like that to deal with, though. Did you do all that correctly?
Never heard of a power loss that dramatic after properly gutting the cat. Good luck.

ShaunB

 

are you sure the conditions were the same? temp and humidity could account for the increase in time.

other than that all i can think of is lose of back pressure droping your low end torque and since it's 1/8th mile you aren't seeing hte topend gains?

 

Most people don't realize how important equal pressure is. Stock the intake and exhaust pressures are balanced. If you up one, you have to up the other.
If you up your exhaust, you can hurt things. Backpressure is a b**ch!!!
Anyway, CAI and airfoil might help balance things out.

 

Thanks for the quick replies! I have a TB airfoil and the moroso CAI right now. The conditions were right about the same the two different times the car was ran at the track. What is involved the gutting the cat, how is the accomplished? Is there a noticable difference in the exhaust tone with simply a gutted cat?

Sorry for all the questions

 

if you've revoved the cat, why are you interested in "gutting" it?


gutting it just means taking it off and knocking out all the crap inside (the catylist). an off road pipe is better if you ever need to put the cat back in for emmisions or to sell it.

considering new cats cost a couple hundred dollars, why go destroying a good one.

with the cat removed (gutted or just a pipe in it's place) you'll notice a definate increase in noise.

 

I dont have the cat removed, I had it put back on after the loss of power I noticed. Did anyone get a code thrown after the cat removal on a 94 or newer car?

 

Mine's gutted, and no.

 

Some of the stuff in my catalytic convertor busted up on it's on - so I just took it off. I am still running stock exhaust at the moment, and everything is fine. I think the only reason I can tell so much of a difference in the noise level is because I haven't correctly mounted the pipe yet - I just have it bolted to the cross member to keep everything from rattling.

I haven't had any codes related to this to my knowledge, and power seems to be equal or maybe slightly better - but nothing at all drastic in either direction.

I am also running a CAI - so I would say that your track time problems are something else that is unrelated. If you have to worry about emissions, you might want to think of your alternatives.

^^^^^^^^^^^^^^
Post #1,000! Woohoo!

 

Explain this back pressure to me. I don't have a cat, previous owner removed it. I think the exhaust tone is horrible. How would I know if I've got bad back pressure, and what does it sound like, cause I think I got it.