cat bashing, pro's n cons

[Dave]

Whats everyones thaughts on removeing or makeing it seem there is still a catolitic converter on the car,

Im asking more out of curiosity, A mate of mine ownes a v8 vr and he said that with a cat it was a gutless wonder, but after he " bashed it out " it ran much better.

Questions,

how restrictive are they

What implications would there be to removeing it, apart from the obvios emitions rules bah !

What benafits if any would there be ?

And last but not least, would ti make any difference to a n/a 1.8l

Im guesing there fairly restrictive by nature, this being caused by hot exhaust gasses being forced through a honey comb of varius metals to burn off fuel and alter the chemical composition of your exhaust gasses.

I think i read on here that in some part of the world these little motors go hard without all the emitions gear.

excuse my spelling, im illiterate and very tired :p

[bornwild]

Well....you'd certainly be able to notice if a car was running a straight through exhaust.

And yes, you would get more power out of them!

[Dave]

as in noise wise ?

I know if they did an emitions test theyd pick it straight away.

[platypus]

well as you have pointed out the whole EPA thing ($10k fine for NSW dunno about other Australian states)
some tunnels have emmisions check cameras too!

you will smell sulphur... it stinks... it will make you want to throw up

[Wraith]

The purpose or function of the catalytic converter is basically to make the exhaust emisions of unleaded cars safe or non toxic !

Removing it is a not a smart thing to do...

Of course removing it will result in better response/power because of less restriction.

Alot of newer cars have more than one fitted to the exhaust system, precat etc. and it's common to delete one for extra performance.

In earlier model cars like the VR mentioned, it would be best to fit a hi performance replacement, (there are high performance models to suit any application, yes it's costs money, but so does everything else) you'll have the same benefit of increased throttle response and power and it's exhaust emisions will remain safe and legal...

But I know the typical young Joe Blow dosn't give a hoot and just wants any cheap or free mod to get more power :rolleyes:

[EL BURITO]

I have a hi flow sports cat. and it is a little loud. and it is leagal. dosent work till heated up thoe u deff dont have the car running in the garage.

[entice]

removing a cat without altering ecu parameters MAY make more power, but may also ruin the driveability. My STi Use to have a catless as well as a cat system, depending on aplication. If it wasnt re-tuned for catless, it ran like a pig, blew smoke, and ran far too rich (ie, less power for same fuel).. on the upside, if i was quick shifting you could see flames exiting the exhaust. On the STI it was a simple proceedure of installing a cat delete pipe for track-use in the place of teh cat (on an APS system).. 6 bolts in total.

Would I recommend it? Nope, not worth the gain, unless you have a specific application, and a specific tune. And yes, the car stunk if idled, and made your eyes water if you hung around it idling... also had a far more "hollow" and metallic sound in teh exhaust when the cat delete pipe was used.

[Dave]

Hmm interesting, like i said i was just asking more out of curiosity, I realy dont have the motivation to go to the wreckers and get a cat i can bash :p just to try it for my self.

Thanks for the replys

[EL BURITO]

there is a member on here with a cali. there cat fell apart and blew out the end of the exhaust.

[stevedee3]

What implications would there be to removeing it, apart from the obvios emitions rules bah !Your engine might operate in limp home mode, due to the post-cat oxygen sensor detecting that the catalytic converter isn't doing its job.

[MatsHolden]

If you were going to go ahead with it (i'm not saying to do it or not to do it) don't poke out the internals... rather just get a straight pipe put through the middle of the cat.

[Dave]

Indeed.............

[platypus]

I have a hi flow sports cat. and it is a little loud. and it is leagal. dosent work till heated up thoe u deff dont have the car running in the garage.

thats the nature of cat convertors... they have to be hot to work...

this is why on many californian car models they have a precat, which sits where a turbo would... this is to enable faster heat up, but this also means you have to have short runners... boo to that!!

on australian cars this requirement isn't there, and emissions are tested at idle on warm engines NOT cold!

[CAL.16V]

makes exhaust hollow and sound like poo

[SKM_87]

pay 2 get a proper exhaust. sounds better. dosnt stink. and theres aint no law 2 screw u over.

[Dave]

I didnt want to do it my self, i already have a system, I was seeing if theres any gains to be had by the removal of this device, it seems there would be, but without the proper map its useless. But flames are cool :p

[Apex]

I have been told that a cheaper option to fitting a sports cat to a small capacity car is to fir a cat-converter of a v8 car or the like??? Anyone got any idea as to if this is true?:confused:

Having removed the pre-catalytic converter from my car I have found it to make a big difference, added response and quicker spool.

[entice]

thats the nature of cat convertors... they have to be hot to work...

this is why on many californian car models they have a precat, which sits where a turbo would... this is to enable faster heat up, but this also means you have to have short runners... boo to that!!

on australian cars this requirement isn't there, and emissions are tested at idle on warm engines NOT cold!


not necessarily true. In Vic, at least, it has to be able to pass same emissions that it did from the factory. that means, if it has a cold cat (mounted as far upstream as possible) and passed cold emissions, it has to be able to do the same if tested later on.

It's also important to note, that some one else mentioned seeing an exhasut shop and "doing it properly". There are varying degrees of "doing it properly". The correct one would be able to have epa certification that it passes emissions on that day. the best would be ADR certification, as teh EPA certification only stipulates that it passed the test ON THAT DAY.

Exhaust systems with ADR certification are few and far between. i dont know of any exhaust shops that would make a custom system and then certify it. Off the shelf top notch systems would be the way to go, if you would want to remain 100% legal, and 100% insurable.... that's a lot of hassle.. and a lot of money. I can see why heaps of people want to keep the "stock" apperance, and bash out the cat... it has been done many times, and is OK short term, but consequences in the very long run (from rich running).

Might be easier to leave it stock cat forward, and cosider cat back options... may not be worth those few extra kw's (if indeed you're fortunate enough to move forwards!)

Some words from experience.. On one of my cars, I had a $700 s.steel Muffler on loan for testing. The car was catless at the time and was doing dyno testing. The expensive muffler gave a 1Kw gain over the stock unit. This meant 184Kw at the wheels as opposed to 183Kw at the time. the tests were done back to back as it was only 2 bolts for the muffler in question to be removed. is that 1/2 a percent gain worth $700? the sound and feel may have been, but the performance gain alone??? Nope. $700 of Octane booster would go a long way....(also can foul plugs with prolonged use). needless to say, the muffler went back and the car retained its stock look.

[platypus]

Some words from experience.. On one of my cars, I had a $700 s.steel Muffler on loan for testing. The car was catless at the time and was doing dyno testing. The expensive muffler gave a 1Kw gain over the stock unit. This meant 184Kw at the wheels as opposed to 183Kw at the time. the tests were done back to back as it was only 2 bolts for the muffler in question to be removed. is that 1/2 a percent gain worth $700? the sound and feel may have been, but the performance gain alone??? Nope. $700 of Octane booster would go a long way....(also can foul plugs with prolonged use). needless to say, the muffler went back and the car retained its stock look.

whereas i found a 7 kw gain, from headers to the muffler with a properly designed system.. cost 700 in mild steel... would i do it again? probably not too soon... might add that was with hi-flow cat, 4-1 headers 2.5inch crush pipe, to lukey sports exhaust... on a 1.6l mazda

[Red AH SRI T]

i'm all for bashing of cats, especially those feral bastards that make a mess of your garden.


Flamin cats!