Removing cat?

Donal199 · 22-06-2010 7:41pm #1

Hi, i have an '02 Honda Civic 1.7 cdti, would removing the cat give it that 'booow' sound? And would it result it the car being more smokey or less reliable?
Thanks.

Atomic Pineapple · 22-06-2010 8:04pm

No that "booooww" sound is an atmospheric dump valve.

It will result in high emissions but I dont think you'd notice more smoke, not sure on a diesel, shouldn't affect reliability too much.

tossy · 22-06-2010 11:58pm

The cat on a diesel is really only there for the greens,a de cat diesel would probably still pass the NCT.

The "booooow" sound is ghey on diesels.

Armin_Tamzarian · 23-06-2010 2:32am

draffodx wrote: »

No that "booooww" sound is an atmospheric dump valve.

booooow

Is it not more of a psssssst sound?

Atomic Pineapple · 23-06-2010 9:31am

Armin_Tamzarian wrote: »

booooow
Is it not more of a psssssst sound?

Normally yes but with a butterfly valve I think its called it changes the sound to a "booooow"

zubair · 23-06-2010 12:12pm

Donal199 wrote: »

Hi, i have an '02 Honda Civic 1.7 cdti, would removing the cat give it that 'booow' sound? And would it result it the car being more smokey or less reliable?
Thanks.

Seeing as Donal is asking about the cat I'm sure he's talking about the exhaust and not a dv. Maybe the "booooow" was confusing.

You don't have to go for a de-cat you could go for a Hi-flow/ sports cat, anything non-resonated will change the exhaust note. As for the side effects of the mod, I'm sure some honda/ diesel owners can give you more info from their experiences and recommend a setup.

Atomic Pineapple · 23-06-2010 12:17pm

zubair wrote: »

Seeing as Donal is asking about the cat I'm sure he's talking about the exhaust and not a dv. Maybe the "booooow" was confusing.

I've never heard an exhaust make anything like the sound the OP mentioned.

zubair · 23-06-2010 12:27pm

I'm not going to discuss whether the "boooooow" is dv or exhaust. Donal needs confirm if he wants real help.

Donal199 · 23-06-2010 1:56pm

The 'boooww' sound is made from the turbo spool, when changing gear or slowing down, it can be heard in some turbo diesels, i just wanted to know if this noise could be heard more clearly if the cat is removed. Its not a dv im not talking about.

Atomic Pineapple · 23-06-2010 2:00pm

Donal199 wrote: »

The 'boooww' sound is made from the turbo spool, when changing gear or slowing down, it can be heard in some turbo diesels, i just wanted to know if this noise could be heard more clearly if the cat is removed. Its not a dv im not talking about.

No, removing the cat will only increase the noise from your exhaust

Armin_Tamzarian · 23-06-2010 2:02pm

I'm still confused.
It sounds like you're talking about the wastegate which can be adjusted though I wouldn't.
End of the day mate it's a diesel, no matter what you do it won't sound good.

zubair · 23-06-2010 2:28pm

Armin_Tamzarian wrote: »

I'm still confused.

Me too!!!!

Midnight_EG · 23-06-2010 9:48pm

Draff, my exhaust makes the booooowwwww

https://www.youtube.com/watch?v=i6-YtRLNomU

metzengerstein · 24-06-2010 9:58am

it usually adds more of a deeper growl ,rather than that awful thiny boy racer sound

i really despise that dump valve noise that someone mentioned above sounds stupid ,ive seen some big moded cars with it and it just ruins it makes them sound whimpy

Armin_Tamzarian · 24-06-2010 1:32pm

metzengerstein wrote: »

i really despise that dump valve noise that someone mentioned above sounds stupid ,ive seen some big moded cars with it and it just ruins it makes them sound whimpy

I love the sound off a BOV.
Obviously not on a diesel though.

Graham_B18C · 24-06-2010 5:53pm

On a proper high pressure turbo it sounds cool, like an Evo, Impreza or Supra

Diageio_Man · 24-06-2010 5:56pm

Meaooo!!!

okane1 · 24-06-2010 7:47pm

draffodx wrote: »

No, removing the cat will only increase the noise from your exhaust

Wrong, nothing to do with the noise from the exhaust. With the decat the car has a much better throttle reponse as the restriction in the exhaust system isn't there anymore. The turbo is able to spin up to speed a bit quicker. You can also hear the turbo spooling up and down giving the noise the OP described (badly!)

I fitted one to my mondeo st tdci and has made a massive difference. If your getting one, make sure the bore of the decat is the same diameter or large than your exhaust, to ensure it doesnt cause a restriction.

Atomic Pineapple · 24-06-2010 7:51pm

okane1 wrote: »

Wrong, nothing to do with the noise from the exhaust. With the decat the car has a much better throttle reponse as the restriction in the exhaust system isn't there anymore. The turbo is able to spin up to speed a bit quicker. You can also hear the turbo spooling up and down giving the noise the OP described (badly!)

I fitted one to my mondeo st tdci and has made a massive difference. If your getting one, make sure the bore of the decat is the same diameter or large than your exhaust, to ensure it doesnt cause a restriction.

I was referring only to removing the cat in the context of noise, of course removing a cat increases performance, however the OP never asked about that.

Removing the cat will not give the OP the atmospheric dump valve type noise that they appear to be describing and it will make the noise coming from your exhaust louder.

Removing cat?

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