Home Made De-Cat - Fitted.. What About Flames?

14th March 2010, 16:32

I have 2 Catalytic converters for my Punto

One, already on the car. Has basically had it. The actually stuff inside has sort of came loose and gingles around in the cat making a horrid rattling noise.

I have another one from another Punto i bought for spares (now scrapped) which i were going to fit.

I thought, could i break out all the mesh stuff like shit out of the broken cat (So its a cat shell, with no cat) and use it as a de-cat? Or would that be a fail?

IOf it didn't work, i'd still have the other cat that's absolutely fine from the other Punto.

14th March 2010, 16:34

it would keep the exhaust tuning the same i suppose and it would have no restriction so i say give it a go if it all goes wrong fit the other one no harm done.

14th March 2010, 16:35

just don't breathe in any of the stuff inside

14th March 2010, 16:40

So its not a stupid idea?

Obv we all know that the exhaust system should run smooth, and unrestricted. But the shape of the cat is like a Rectangle. Wouldn't the gases build up in there, thus loosing the idea of a 'de-cat'

I'm, aware you can get £20 for a cat too at the scrappy. If i bust out all the crap inside, and all fails. Would they still accept the cat in one hand, and the cat inserts in the other hand?

14th March 2010, 16:43

Yes mate doing that would just be exactly the same as getting a normal decat just as long as you make sure you get all the old stuff out... and if the cats dead then the precious metals probably arent worth anything. the shape of the cat wouldnt make much difference to back pressure as its not very long so the pressure will drop as the gasses go in then go up when they get forced through the narrower pipe again, so thered be no difference really, its quite far away from the manifold anyway. Unless your cat is in the manifold?

14th March 2010, 16:55

Nope. The cat is where the the cat is on a Normal Mk1 Saxo. The next section from the Maifold.

Hmmmm.... Do i throw £20 away for something that may not work?

14th March 2010, 17:00

what do you mean may not work? how can it not work?

14th March 2010, 17:05

Perhaps it might make my car smoke, sound rough, sound like a V8 or will smell like a petrol station when driving down the road?

14th March 2010, 17:53

I did that on my Saxo, worked nicely lol.

14th March 2010, 18:58

Clear it so its just the cats shell, then weld a pipe throught it so it stays the same diametre

15th March 2010, 16:43

I've done this on my mk2 Furio. Sounds great in the high revs. It doesn't sound quite the same as a proper decat pipe though (i used to have one on the same car). You get a slight kind of whistle noise as you really accelerate but hit about 4k revs and it sounds lush.

15th March 2010, 17:17

Wouldn't it be easier to fit the good cat for now, get £20 for the old one and buy a 2nd hand decat pipe for about £40?

15th March 2010, 17:19

And if you take all the inside of the cat out it will still fail an emmissions test on the mot?

15th March 2010, 19:56

hollowed out cat will act as a massive expansion chamber, not the best way. cut it in half and weld a pipe inside

15th March 2010, 20:01

Had this on my westy, didnt know about it til MOT time, was completely empty inside and now i have a proper cat on i can tell the difference from before.

Dont see why doing it would cause a problem (except for MOT)

19th March 2010, 17:05

I took my cat off, bashed the honey comb out. I as really surprised how strong that stuff is. I thought it was paper. But its like plaster, that's the only way to describe it.

Results:

Fitted it back onto the Cunto. And VAROOM! It sounded aright. I guess i'll have to wait a few weeks for the soot to build up inside as it was VERY clean.

Took it for a spin, didn't notice a thing tbh. I'll wait a few weeks

All i want is it to back fire, and go POP.

Its a standard exhaust system, but can this be done?

19th March 2010, 17:08

All i can smell is the dirty smell of burnt petrol... Yummy.

19th March 2010, 17:15

I hope you didn't breathe any of it in as it's filthy stuff and won't do you the greatest good.

Looks good though - nice a stealthy for the casual onlooker

19th March 2010, 17:17

NO I DIDN'T BREATH ANY IN

I did it inside a bucket, so wouldn't blow away and its such fine dust. What makes them so expensive, i couldn't see any platinum or what ever was supposed to be inside.

Would i be able to have a 'Popping' noise. and seriously, will i notice any powah gains? So far i've not noticed anything.

19th March 2010, 17:19

Quote:

Originally Posted by dannyboy2005

NO I DIDN'T BREATH ANY IN

I did it inside a bucket, so wouldn't blow away and its such fine dust. What makes them so expensive, i couldn't see any platinum or what ever was supposed to be inside.

Would i be able to have a 'Popping' noise. and seriously, will i notice any powah gains? So far i've not noticed anything.

lol, prob not notice anything tbh - what exhaust system you running?

It's all such small amounts that you won't find a chunk of platinum in there ! They can separate it all etc. to get what they want out of it.

19th March 2010, 17:23

Standard, factorie exhaust system.

Standard Manifold
De-Cat
Middle Silencer
Back Box.

The pikeys would go through half hours hard work, pile driving a 3ft socket down the system to get it out?

19th March 2010, 17:40

you prob won't hear any different with a standard system but just with a decat, neither power increase.

It won't be like strapping a rocket to the back of the car

19th March 2010, 17:41

I'd prefer this setup as you're keep the exhaust tuning the same as the factory due to the Cat being an expansion box too.

19th March 2010, 18:11

As i mentioned earlier, it's contently stinking of fuel. (I can understand why)

What i was thinking would be utter LOL is to make a flame come out the back?

Can i do it? And, is all i need a spark plug, connected to the ignition connected to a 12v power supply.. Or do i need a HT box + HT cables? (Like a standard spark plug in the engine?)

19th March 2010, 20:09

You will need the spark plug connected to either a relay or a coil but i seriously wouldnt bother mate. As for the decat i've got a standard system apart from having the cat hollowed out like yours and and a can style back box and it pops really well once its coated up inside. At first it sounded a bit tinny but soon sounds the dogs nuts with a decent back box.

19th March 2010, 23:27

Quote:

Originally Posted by 5trudd3rs

You will need the spark plug connected to either a relay or a coil but i seriously wouldnt bother mate. As for the decat i've got a standard system apart from having the cat hollowed out like yours and and a can style back box and it pops really well once its coated up inside. At first it sounded a bit tinny but soon sounds the dogs nuts with a decent back box.

I cant get a back box unless i hack saw the old back box. you see, my exhaust system comes all in one. From the cat to the back box is all one piece

20th March 2010, 16:43

This all sounds very interesting tbh lol

probs would of been easier to just weld some pipe up though

20th March 2010, 16:55

if you want popping buddy run a piper/super sprint backbox as they pop a fair bit, cat back system will pop more then a backbox
just to make it more popperlicious fit a 4-2-1 mani.

in other experiences ive also found that big bores pop a fair bit, as in universal big bores such as savage and rage.

o dear if you want a flame come out the back place the spark plug near the end of your exhaust as if you put it near your cat the engine may suck it back in??
then just link it up to a power supply and a switch. just have a fire extinguser ready as ive seen videos where the back of the car catches fire. quite funny to watch tho. just make sure your sesable in doing it

21st March 2010, 18:09

Yeah tbh i think flame kits are a bit risky. I've seen pleanty of videos of cars going up in flames where the engine sucks some of the gas back in. Ah, i see about your exhaust. I would probably save a bit of money and buy a complete system like everyone else is saying. Even if you buy a stadard saxo exhaust system from a scrappy and then add on the bits you want (de-cat, back box, mani etc).

21st March 2010, 20:09

kid, its a 60s. its not going to get faster, just louder. ran my old punto without a backbox (rust ftl) and it just sounded like a tank.

Quote:

Originally Posted by dannyboy2005

I cant get a back box unless i hack saw the old back box. you see, my exhaust system comes all in one. From the cat to the back box is all one piece

you can get them in more than one piece, just takes asking. wether it fits right is beyond me, but theres 2 types, the one me and you had (cat back all in one piece) and one thats split up (silencer, pipe, backbox)