Brent Swan

I guess gutting the cat,means that you took it off,right?What performance could I expect from doing this?and would it affect any of the emission stuff?Pros and cons,need some info.What about the sound?seems to me that it woud be pretty loud.If I did get this done,does all muffler shops do this?or is it hush,hush if I did have it done?

shutch

i don't believe gutting the cat affects emissions, but gutting the cat has something to do w/ cleaning it's inards. i'm not sure as i haven't done it. if youi live in an emissions state, i wouldn't do it until you get some more advice. NO muffler shop is allowed to touch the cat until it is proven that it is faulty and needs to be replaced. running w/o one shouldn't make the car any louder, that's what the muffler is for. not sure on the hp gain, if any.

Brent Swan

Thats what I was wondering.What I really meant to say was more on the subject of removing the cat.Is it worth the trouble?

87formula

Having done this already myself, I know it does make the car louder, but it also sounds much better... I haven't had any engine light come on as of yet (I removed my cat about 1 year ago). It does make the exhaust flow easier which will make the uppper end run a little hotter (in a heat sence not a hp sence) although i am not sure if will add any hp it does sound much better. I removed mine because the cat became plug, but I replaced mine with a straight piece of pipe instead of gutting the cat. If you gut the cat put a piece of pipe through it other wise your exhaust will get "hung" in the larger circumfrence of the covertor case.

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1987 Firebird Formula
305 LG-4
GM Vortec heads 2.02x1.6 valves
Crane CompuCam 2030
700-R4 Trans
4 barrel quadrajunk remained by holley (this carb stinks!!!)
edelbrock performer intake
Hypertech Thermomaster Chip
Open Element Air Filter
No Cat with Straight pipe (Dynomax muffler rusted apart and fell off probably could not stand the heat )
Accel H/P Coil

- Soon to be installed
383 stroker (built and ready)
NO MORE COMPUTER CRAP
700R4 Lockup kit
Edelbrock TES
True Dual exhaust or 4 inch single pipe to dual 2 1/4"
Stall convertor

blacksunshine'91

iTrader: (10)

Ah, yes it would effect emissions. That's the purpose of the cats. If you have emissions in your area then I wouldn't advise gutting it. Besides, a straight pipe only gains a few(approx 5) hp over a performance cat.

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'91 GTA with TPI 350 & T-Tops. Just a few mods, if you want to find out just line up next to me at a stoplight!

Added bonus:
Wife's car is a '00 Grand Prix GTP!

Brent Swan

I don't think they have emissions in my area.Is a performance cat worth buying?I Know 5hp is not that much,but when your trying to get the most out of your engine without sacrificing the possibility of other things to go wrong,I'm all for it.Who sells a good,quality per.cat?

Suaveat69

Gutting the cat will not affect emissions in most cases. It will have a more higher pitched sound though. Some say that the HP will increase and some say decrease. Have ur muffler guy put a straight pipe through the cat. You can legally(like we need a freakin EPA *******s telling us) replace the CATS after 50,000 miles or before 50 as long as it is damaged.

Curse Z28

gutting your cat will most certainly affect emissions, the whole point of them is to cut down the amount of hydrocarbons,carbon monoxide,carbon dioxide,and nitrogen in your exhaust.
I had mine removed and a straight pipe put in, it was definitely louder, but not drastic.

I recommend having it/them removed and replaced with a straight pipe rather than gutting them, no reputable muffler shop will do this (or atleast admit to doing it) as it is MUCHO illegal to tamper with emissions control equipment.
Its definitely a no-no if you live in an emissions state. Here in florida we can pollute all we like


[This message has been edited by Curse Z28 (edited June 24, 2001).]

90Iroc-Zee

Okay they did a test on this in car craft on a 305 TPI 5spd 3rd Gen with a Vortech. It had dual cats and the dyno showed w/o cats it netted a 3.4 hp gain and a 10.2 lbs/ft of torque loss. So you take your pick, after reading that I said after I get my cam and can AFFORD to lose some torque will I gut my cats :P

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1990 G92 5spd LB9 - 3.42

Accel Ignition/Wires (8.8mm), Advanced Timing, TB Bypass, Ported and Gasket Matched Plenum, Synthetic Motor Oil, 160 Thermo, TPIS Airfoil, K&N Air Filters, Centerforce I Pressure Plate and Clutch, Edelbrock TES Headers, Dual Cats, Edelbrock RPM Series Catback

14.4 @ 94mph w/2.0622 60ft

Soon To Come

AFPR, Underdrive Pulleys, Short Throw Shifter, Intake, Cam

6-0 Against Rustangs = )

RW91B4C is there anyway I can contact you? We have the same cars with almost the same times, it could be good to give some good tips to eachother

Omar

Gutting the cat WILL affect emissions. It may not be enough to fail a car, but your numbers will go up.

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1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

Suaveat69

Please. As lond as the car passes with the cat it will pass without the cat. Who cares if the numbers go up. I have had mine gutted for years now and passed every emission test.

84TransAm

I thought I had a cat, but when i took it off to gut it it was already done suprise!! I don't have any welding materials, so I clamped it in the front and it leaks. My inspection is due, Virginia has the visual, so guess who's getting a new cat put on tomorrow?

Morale of this story?? Leprechauns can't be caught, dont even try. Or If you don't have welding equipment or acess to it, don't attempt it.

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--Steve S--
1984 Trans Am 305 LG4, 5 speed Daily Driver, Flowmaster 80 Series
Holley 600 cfm & vacuum advance
Soon: Edlebrock Intake & TES

TRAXION

Gutting the cat will ABSOLUTLEY affect emissions. The catalytic converter is the one piece of hardware in the emissions system that seriously reduces emissions. Been there done that. Went with gutted cats and failed miserably. Put my good dual cats back on and passed with almost zero emissions. Plenty of other local guys around me have done the same.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

MikeS

Suaveat69,

what kind of tests do you have to pass?

Suaveat69

Almost the same test as in the left coast of the world. I am in Pittsburgh. Anyone out there run the formula for emission through the cat and find out what chemical comes out. Have ur organic teacher do this. The end product binds with ozone and destroys it. I dont know about anyone else but if i can find them i willpost my emission slips with and without the converter. Passes easily without it.