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Punching The Cat Converter On Rb25de

D33J

By D33J,
in Engines & Forced Induction

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D33J Explorer

D33J

Posted
Posted

Hey guys, I was looking to punch the cat on my gts r33. I was wondering if any1 has done this? because the oxygen sensor will go spastic and the fuel mixtures will change. Basically im wondering if the car will begin to run lean or rich. Since lean is damaging to an engine.

Richening is ok, cos it throws flames :D

cheers

GTS4WD Grand Master

GTS4WD

Posted
Posted

Punching a cat is mean for a start.

Punching the cat guts out does not really have that many benefits.

For a start your going to cover the back of you car in black carbon which is very hard to get off.

Your going to going to see the occasional flame exit - not cool at in appropriate times i.e around the wrong crowd.

In terms of sound, I have heard it swinging both ways, louder and quiter. I assume it depends on exhaust modifications, engine mods, the type of engine etc.

And in terms of performance. Very little in an NA. There isn't a very large volume of gas exiting the engine. So minor things such as catelitic converters will have little restriction.

Johnny Veteran

Johnny

Posted
Posted

Hey mate, i put a straight pipe in my r33 gts-4 NA in 2001 and all it did was make the exhaust sound terrible at cruising speeds.

Response increased but i put back the stock cat about 3days later in my garage.

Turbo cars definitely run better without the cat but the turbo acts to mask the 'rasp' metallic noise which is not plesant.

A high-flow cat is your best bet for both worlds and wont get you into trouble; you can really tell on an NA.

N-DAWG Mentor

N-DAWG

Posted
Posted

lol nice one cris

An ECU reset (ignition off, disconnect negative terminal, brake 10-15seconds, reconnect) will allow the car to relearn the difference in air flow, which as Cris said on an N/A isn't going to make much difference.

Unless you were upgrading extractors and catback system, and then the cat was creating a restriction, then you would probably want to look at gutting/changing the cat.

Running rich for the sake of flames and SFA difference to your performance is a fine way to unnecessarily increase fuel consumption too :)

What's the legalities on gutting out a cat anyways? Is it one of those things that's illegal if you get caught? Personally I would do it right and swap it to a high flow one should the need arise.

If you're looking for low cost ways to increase the performance, look at making a CAI with a pod filter or even just swap the filter with a high flow K&N Panel or something similar. You'll probably notice more difference doing that then gutting the cat on an N/A, particularly if you've got an old standard filter.

Eug Grand Master

Eug

Posted
Posted

a gutted cat, flames and all that carry a maximum of $10,000 fine.

not only is it a highly illegal 'mod', it's also extremely damaging to the environment

one of those things you don't bother doing - especially if high flow cats are <$200

Vik Mentor

Vik

Posted
Posted

Bashing out a cat, just to get that extra zing.. while hurting the environment and a potential life changing fine ?

Seriously, no offence but bash the cat across your head, lol.

High Flow Cats are cheap as these days, will get you more of a zing, and will look stock / avoid a 10 000 fine!

So i'd go the alternative if i was you :P .. but i have to admit the flames look cool lol :)

MRXTCZ

WYTSKY Veteran

WYTSKY

Posted
Posted

LOL, remove from cat from car, bash yourself on the head with it and then spend 200 dollars and get a normal highflow.

I gutted my stock cat because I already had an exhaust system and just turboed the car and it gave me an extra 15kw, in a turbo car... in an n/a you would get 0-2kw? if your lucky...  it may actually be increasing your back pressure atm so if you took it out you may loose power to!  

btw... an extra big dont do it (ontop of killing the environment and getting massive fines and black crap building up) you get carbon monoxide coming up the back end of the car.... the stuff that petrol companies say "cleans your engine" crap. it is a horrible yellowy browny colour and the back of your car will be completly covered in it in about 2 weeks. the only way to get it off is about 30 mins of scrubbing with cut and polish and degs each week..... its even worse if you have a white car like mine! and you always watch your back for the cops about that... cuz a cop that is switched on could tell and theres your 10g's gone....

I ended up getting not a highflow cat, but a metal cat... better flow (costs abit more) but it is just about as flowing as a gutted cat, so much so that I did not loose any power putting it on my car.

Adam

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