HotBoy

My cats have not been changed in 210000miles and I think theymay be toast.
I have some time until my smog so until that time I am looking at going straight pipes and removing the primary and secondary cats. Leaving the resonators and mufflers.

I found some info after doing a search but not that much.
I would like to hear from people that have done this and what trouble it gave them. I have a 92SC400, I am going to look tomorrow but if I remember I think I saw an O2 sensor after the cats when I was doing a tranny fluid change.
what do I do about this ?

aliga

iTrader: (147)

you can get a o2 simulator from caspers electronics for around 55 bucks.

97SC

Even though you have high miles, Cat converters in general will last the life of the vehicle unless your A/F mixture is off. If you want to gut them get a big screwdriver and a dust mask and start pounding away at it. I wouldn't suggest it though, and you will still need them for smog. How about replacing them with an aftermarket high flow, it'd be about the same price as a stock replacement or cheaper(ie catco, random technology) Why do you think your converters are bad though? My converter on my honda looked new after 225K miles... Does your exhaust smell like rotten eggs(sulfur)? If so then it's a bad converter, if not then i'm sure they're fine.
Ohh and one more thing. Replacing your cat with a straight pipe can get obnoxiously loud on some cars so be careful

JBrady

Gutting the cats will actually create a large plenum out of the catalyst shell. This will kill velocity and kill low speed torque. It may even reduce high RPM power due to turbulance. The cat shell also becomes a sounding board creating a racket above and beyond the fact that the car is raspier sounding and louder at the tailpipe. The only correct way to due this is to replace the cat with a straight pipe. Some even put the pipe inside the cat body to make it visually look like it still has cats.

As far as power goes the cats outflow the stock mufflers and resonators.

www.planetsoarer.com

Unnatural

This is absolutely correct. Are you wanting to gut the cat itself or just replace them with a straight pipe? I would just recommend replacing the cat with a high flow unit as mentioned above or just leaving them alone until you can afford it. That said, a straight pipe (or test pipe) will typically only provide marginal gains on a N/A car. The gains are not usually not worth the trouble when emissions testing time comes IMO.

~Brendan

97SC

Very true, in fact replacing your converter is the highest $/hp mod that you can spend your hard earned money on. He asked how to gut it and I told him, not that I recommend it, especially with CA emissions laws. If you want to pass the visual though, as mentioned, running a pipe straight through is the best way...