Cats (Page 1/2)
85fieroguy SEP 30, 10:08 PM
Settle an argument between 2- 85 GT owners of V-6's One took off his cat converter and has no problems, the other says taking the cat converter off affects performance. Whats your opinion.
Patrick SEP 30, 10:13 PM

quote
Originally posted by 85fieroguy:

Whats your opinion.



Ask the person driving behind the catless Fiero what their opinion is.
pmbrunelle SEP 30, 10:33 PM
As a stock Fiero has no post-catalyst oxygen sensor, the presence or absence of a catalyst should not have much effect on engine operation. The ECM is not aware of the catalyst.

If the catalyst was in good shape, removing it will remove some restriction and free up some small amount of power.

If the catalyst was clogged, removing the catalyst can make the engine go from not running correctly whatsoever to running fine.
wftb SEP 30, 10:35 PM
if your cat is old and plugged up with 30 years of crap, taking it off will improve performance and help you fill the world with NOX and carcinogenic particulate. Replacing it with a new cat will improve performance an equal amount and improve the environment. Your choice.
cvxjet SEP 30, 11:52 PM
The new cats are a hexcel matrix that creates no real backpressure- so removing it only makes for more pollution...If the cat-less guy likes pollution, tell him to take up smoking 10 packs a day!

The older cats created some back pressure- which would appear to make removing it an improvement- But most computer-controlled engines are tuned/programmed to have some back pressure- so contrary to "Common knowledge", removing a cat could HURT performance!
theogre OCT 01, 07:06 PM
All monolithic cats have very little to no back pressure.
Fiero V6 has them but many are plugged or worse for engine burning oil and other problems.

Fiero L4 and others regardless engine displacement had (Some still have) "Pebble Bed" cats that does cause some back pressure because of cat design. Has several names over time but all are based on Pellets in them.
Years ago Pebble Bed units could be reloaded/rebuilt by installing new Cat Pellets thru a hole in case w/ a new plug in the hole after.

An old Pop Mech article cover old types.

Burning oil, run rich or lean, "burning" coolant, and other engine problems will plug or poison the cat.
Coolant leaks from intake manifold problems etc. are common cat killers.
Type of Engine Oil and Additives you might add to the sump matters too. Cats get poisoned w/ Zinc (AKA ZZP) and other things sim to having Lead Gas before was banned in most places. Is why new(er) API SJ SL SM and SN have less Zinc. You adding more zinc to current oil types are not good because most use way too much, more then obsolete SF and SG oil or even older classes.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Kevin87FieroGT OCT 02, 09:41 PM
To answer your question: Had an 86 SE (2.8L) without the cat, straight pipe, but OEM muffler. Put a high flow MagnaFlo universal cat on it. Piping was all stock size. All I noticed was the raspy ness of the exhaust minus the cat was gone after installing the MagnaFlo. Tone was nice with the MagnaFlo. As for mileage or performance there was ”no noticeable” difference! This was on a perfect running 2.8L (37,000mi).

The previous owner of our car reported to her mech that the car had no power going up hills. The mech removed the cat and put the straight pipe on. On our inspection of the old cat, which was in the trunk when we picked up the car, looked good visually. However, you can’t see the center of the cat so who knows if it was good or bad. the straight pipe was the mechs fix. It was nice though that we had the OEM cat. We turned in the OEM cat at a metal scrapper for $100 which payed for the new MagnaFlo (approx $70) and the cost to have it welded on that straight pipe ($30). Ended out being a win/win, new cat and better exhaust tone!

Having the cat will make the exhaust smell better while idling, if ya give a hoot. Who cares about the guy behind you, if he can smell your exhaust he’s to close anyway.👍

[This message has been edited by Kevin87FieroGT (edited 10-02-2019).]

Steel OCT 03, 09:01 AM
Catless, no mufflers install a j-pipe to tune the sound on each side. I use to have a video of mine setup with that I'll see if I still have it when I get home later.
Tony Kania OCT 03, 09:10 AM
Mine sounds awesome with no convertor. Stinks to high heaven and pollutes the air. I imagine I will put a new convertor on when I get to it. Getting older in years and wouldn't mind a cleaner, quieter system.

I am all for running with a catalytic convertor. I believe that I am wrong and would like to correct that one day.
sourmash OCT 03, 10:30 AM
Catless cars stink up the general area. Has nothing to do with anyone following too closely. My neighbor and his kid doesn't deserve to have to smell my exhaust on his own property, but he will if start the one I own which was bought cat deleted from someone here. It'll give you a headache or a smell you can't get out of your clothes, hair and nose hair.
I have property in a poorer section of town and the cars in that area make the whole neighborhood worse with their smells. Stop signs, red lights (even after they're long gone) parking lots, drive thrus. It's not just me who thinks that people who drive them are not the sort of people I would trust to tell me I dropped 5 dollars at the convenience store register. There's usually dents in the car, mismatched rims and red tape over the cracked tail light, but plenty of money for cigs and tattoos.

How's that for profiling?

[This message has been edited by sourmash (edited 10-03-2019).]