5 litre exhaust backfire / crackle, bad for cat?

[Cobez]

Hey guys, as i'm sure most of you know, the big crackle and backfire kind of noise you get from a 5 litre with no resi when you give it a bit then back it off halfway between 1st and 2nd generally, is this bad for your cat converter?

I know all that noise is just unburnt fuel, but is the pressure through the exhaust pipe enough to blow the cat at all? If not, what damage can it do? I have done it a couple of times as if can't really be too good for your engine i would imagine.


Cheers

[Reaper]

All in all it won't be good. A bit of unburnt fuel from time to time is no big deal, continually it will reduce it's overall life significantly.

Reaper

[Cobez]

That's what i assumed, hence why i keep that to a minimum, doesn't sound as great as i used to think it did anyways.

[Zuicider]

well put it this way, i left a plug off terminal when i did my extractors, the unused fuel trapped itself in the cat and ignited and caused the new cat to only last 5 minutes :P

[Cobez]

Hmmm, not good at all ^^^

It's ok, it's better i don't do it at all anyway.

[greenfoam]

Mine crackles and pops like crazy (done it thousands of times) and had ZERO damage when I was redoing the exhaust the other day, it sure sounds like it would blow a hole in it but no such luck

[Cobez]

Yeah see that's what i thought too, sounds like the back pressure coming through would eventually blow the cat out. I'm gonna buy another stock cat when i get my 3" exhaust fitted in January. Don't really want to fork out for stainless cats etc, stock cats still work rather well so i'll stick with them.

[VNexecutive]

mine crackles and pops like crazy too. is this cos i have no mufflers or resi's past my cat at all?

[Cobez]

It would be because you have no resi. I have a muffler after the cat and it still does it heaps. But not having the muffler would increase the noise though.

[VNexecutive]

yeah it gets pretty loud when it does it. thanks for that anyways

[greenfoam]

You can tune it out with more advance when you back off bit since it doesn't seem to make a big enough bang to break the cats I don't worry about it too much

[stocky]

any idea how much advance your dizzy is set to cobez?

[Cobez]

Nah no idea man sorry!! ^^^

Sweet, i guess if the cat blows (which from what everyone has said it should be alright), another stock cat won't break the bank i'm sure.

[padrickz88]

for the sound, id would be worth killing a cat lmao

[Cobez]

Hmmm, i used to think it sounded good, now i reckon it sounds ****.

[Lumps of cheese]

Meh, don't worry about it. Stock cats are fairly cheap anyway. Mine pops a bit as well and i'm running the stock cats but i was told that it won't hurt it at all.