No cat? Half cat? New Cat?
#1
No cat? Half cat? New Cat?
I just got my 94 Z-28 automatic up on a lift cause I heard a rattling noise from underneath the car. Turns out something in the cat is broken and rattling around, probably some of the catalyst wafers inside. The cat is connected to the Y pip making a stock new one too expensive to buy. so emmissions problems aside, should I hollow out my existing cat? Should I dump out whatever is broken and keep any good wafers inside the cat? Or should I buy an aftermarket one and weld it in place of the old one ? Has anyone ever tried any of these options? What are some problems with too little back pressure or too much? Any suggestions would be great.
#2
Re: No cat? Half cat? New Cat?
Gut the cat. The catalyst is not a series of "wafers". The catalyst is a honeycomb brick. It is quite tuff and hard to get out. No problems with lack of back pressure without a brick ,the stock gutted y-pipe provides way too much.
#3
Re: No cat? Half cat? New Cat?
If that happened to me and I had your car I would rip the GUTS out the cat and if Emissions is an issue....at time of Emissions I would just get a highflow random tech cat and have them weld it in and after that your all good. Save money now...pay later kinda thing.
#4
Re: No cat? Half cat? New Cat?
I just pulled my manifolds and cat off, and my cat was already gutted - meaning it self gutted after all these years. Funny thing is, I never failed emissions! So I put in a 3 in pipe to replace said cat. Haven't tried to pass the new setup yet.
#5
Re: No cat? Half cat? New Cat?
Yes, your cat is bad. That same thing happened on both my Zs. I would recommend replacing it with a carsound unit. (ebay ~$35-$40)
Gutting it will make your car louder, but it doesn't sound good in my opinion. So if you don't want to replace it, at least replace it with a pipe.
Gutting it will make your car louder, but it doesn't sound good in my opinion. So if you don't want to replace it, at least replace it with a pipe.
#6
Re: No cat? Half cat? New Cat?
Thanks for the advice, I guess I'll just pull off the y pipe and rip the guts out of the cat. I wonder where the rumor that ripping off the cat could screw up your engine came from. Maybe other less restrictive cars get ****ed up by pulling off the cat.
#9
Re: No cat? Half cat? New Cat?
A little humble advice: completely gutting your cat will make a "hollow" sound to your exhaust note. I tried something that worked pretty good. Rather than gutting it completely, just make a hole through the catalyst the same diameter as the in-pipe to the cat. Basically you're making a straight-through muffler and it doesn't have a hollow sound at all.... at least on my car with the MACs and Hooker cat-back it doesn't. It made the note deeper and it pulsates harder. Sounds very clean with no rasp.
I also thought about just putting in a good stock cat(or high-flow cat) and dumping it before the axle like a single-shot design (getting rid of the cat-back). A buddy of mine did this with his 97 Z71 and it sounds awsome. No popping and one of the deepest/cleanest SBC exhaust tones i've ever heard. Saves a little weight too.
I also thought about just putting in a good stock cat(or high-flow cat) and dumping it before the axle like a single-shot design (getting rid of the cat-back). A buddy of mine did this with his 97 Z71 and it sounds awsome. No popping and one of the deepest/cleanest SBC exhaust tones i've ever heard. Saves a little weight too.
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