endrop - for all your online needs

Tuning DE-CAT questions

Currently reading:
Tuning DE-CAT questions

kyle96

kyle96

Patron member
Parked in the garage
Joined
Jun 3, 2013
Messages
507
Points
105
Location
Middlesbrough
Hello all,
I'm past the 'how to make my 1.2 faster' stage so don't worry :p
However I'm not really knowledgeable on the subject of decatting,
I have a good friend of mine that is going to do me a full service, and can also legally do mot's too.
He has offered to decat my car for me, so i was wondering,

Will this lose too much backpressure and cause the engine to actually lose power?

Would I need a remap to actually make any benefit out of the decat?

And how could I get 'clocked' by police? Is there any tell tail signs of a decat? And if worse came to worse, whats the penalty for a rode side emissions check fail?

Thanks for any advice / guidance :)
 
kyle96 said:
Hello all,
I'm past the 'how to make my 1.2 faster' stage so don't worry :p
However I'm not really knowledgeable on the subject of decatting,
I have a good friend of mine that is going to do me a full service, and can also legally do mot's too.
He has offered to decat my car for me, so i was wondering,

Will this lose too much backpressure and cause the engine to actually lose power?

Would I need a remap to actually make any benefit out of the decat?

And how could I get 'clocked' by police? Is there any tell tail signs of a decat? And if worse came to worse, whats the penalty for a rode side emissions check fail?

Thanks for any advice / guidance :)
Click to expand...
I would put a cat back, which is having a straight through with a cat left in it, I have one of them, iit would fail and mot and you would have to get a re map, police would be able to tell because it'll draw attention to you by being loud and popping and banging, but if it takes your fancy
 
Not sure what the penalty is. I'd certainly expect the car to be impounded. It's a surefire MOT fail, so your mate is either pulling your plonker or about to get his employers into a world of pain.

You might gain 2 or 3 bhp -- you won't feel the difference. The car will probably be a little noisier.

Turbos don't like backpressure -- at least, when on boost -- so the best exhaust is a short, straight one. That'll get you busted in double quick time.

Generally, to take advantage of a decat you'll need to be running a car in an engine spec which demands very rich mixtures (which will destroy a CAT in no time at all). But that'll need more than mapping. And you'll fail emissions.

The tell tale sign of a de-cat is no cat! Especially easy to spot on a car which should have a manicat. And weird emissions.

Expect a police officer accompanying the VOSA crew to ring your insurance company to tell them that your car has been modified and is illegal.

You might get away with it for years, but the consequences can be devastating.

For all that, I can't think of a reason (apart. maybe, from shortened gearbox life) why a properly set up T Jet can't deliver 200bhp with a CAT.
 
the 1.2 8v has a straight through to begin with does it not? I'm certain it has no mid silencer, and I've already replaced the backbox with a free flowing one, so the only other restrictive point I can think of is the cat.

There would be no benefit replacing the existing cat back with a stainless is there? It would just be replacing the pipe with a different one.

The exhaust is quite loud as it is and I don't have much police hassle tbh
Thanks for the reply :)
 
fingers99 said:
Not sure what the penalty is. I'd certainly expect the car to be impounded. It's a surefire MOT fail, so your mate is either pulling your plonker or about to get his employers into a world of pain.

You might gain 2 or 3 bhp -- you won't feel the difference. The car will probably be a little noisier.

Turbos don't like backpressure -- at least, when on boost -- so the best exhaust is a short, straight one. That'll get you busted in double quick time.

Generally, to take advantage of a decat you'll need to be running a car in an engine spec which demands very rich mixtures (which will destroy a CAT in no time at all). But that'll need more than mapping. And you'll fail emissions.

The tell tale sign of a de-cat is no cat! Especially easy to spot on a car which should have a manicat. And weird emissions.

Expect a police officer accompanying the VOSA crew to ring your insurance company to tell them that your car has been modified and is illegal.

You might get away with it for years, but the consequences can be devastating.

For all that, I can't think of a reason (apart. maybe, from shortened gearbox life) why a properly set up T Jet can't deliver 200bhp with a CAT.
Click to expand...

He is his own employer, well at least he tells me this, I have a lot of trust in him though, He passed his own mot with his astra decat.

So it seems a decat for the 1.2 is not worth the effort, from what you've said.

I understand the risks you've pointed out but I can't imagine police checking if I have a cat or not, most of the time all I get asked is who owns the car and who is main driver, which I love answering :D
Is there really that much of a risk? Knowing people that drive round all day long without cats and the coppers not even blinking an eye sort of give me a bit of confidence.

I would of thought though however that any difference on the 1.2 would be noticeable considering how underpowered it is stock, I can feel the difference with the k&n panel filter tbh
 
I did a decat on my 1.2 by using the exhaust mani off a punto 75.
Car is more torquey and revs happier but not much power gain. I have a gsr fitted as well.

My car runs on lpg so mot emissions are very low and it passes without any probs. The sound is a bit raspy at full throttle but definately not loud
 
I missed the 1.2 bit!

Nah, the biggest problem you have is a tiny little engine dragging round a big shell. The 1.2 is a fine engine, but really needs to be popped into something like a Cinq or Sei. In a minor way, a 1.2 Cento (even an 8v) is a giant killer. Or sell up. buy a T Jet.

The standard police, even the traffic cops, will just ask you the normal questions unless you really annoy them. But hidden amongst the traffic police are the elite crew who will deal with specifics and accompany VOSA teams.
 
chricol said:
I did a decat on my 1.2 by using the exhaust mani off a punto 75.
Car is more torquey and revs happier but not much power gain. I have a gsr fitted as well.

My car runs on lpg so mot emissions are very low and it passes without any probs. The sound is a bit raspy at full throttle but definately not loud
Click to expand...

That sounds interesting! Where did you get that manifold from?
Probably not worth going that far for me though, although i'd like too

If you fancy selling the gsr you know who to pm ;)
 
fingers99 said:
I missed the 1.2 bit!

Nah, the biggest problem you have is a tiny little engine dragging round a big shell. The 1.2 is a fine engine, but really needs to be popped into something like a Cinq or Sei. In a minor way, a 1.2 Cento (even an 8v) is a giant killer. Or sell up. buy a T Jet.

The standard police, even the traffic cops, will just ask you the normal questions unless you really annoy them. But hidden amongst the traffic police are the elite crew who will deal with specifics and accompany VOSA teams.
Click to expand...

Id love a tjet, but I wouldn't get near enough what I spent on the current 1.2 (about 3.2k) If I sold it

I also want to move onto a different car when i finally decide to sell up, Unless maybe an abarth, but a well tunable engine is probably next for me, maybe a 1.8t ibiza, or if I'm doing well, a new 2l tsi

I suppose knowing my luck however that elite crew would pick me out of the thousands to pick on
 
kyle96 said:
That sounds interesting! Where did you get that manifold from?

Probably not worth going that far for me though, although i'd like too



If you fancy selling the gsr you know who to pm ;)
Click to expand...


I got the manifold off an old scrapped punto for less than 15 pounds ;) then i had to drill a hole and weld a nut to it to hold the lambda sensor.

My gsr is actually for sale but I live in Malta so shipping wouldn't be cheap i think
 
chricol said:
What do you mean exactly?
Click to expand...

I dont know what he exactly means but your in a 1.2 unless you spend mega money on things like re-map, injectors, cams you won't see much gains for your money. You say you have spent a lot already, why not call it quits engine wise and save up till you can get a tjet or a mjet or something not fiat...
 
lou5590 said:
I dont know what he exactly means but your in a 1.2 unless you spend mega money on things like re-map, injectors, cams you won't see much gains for your money. You say you have spent a lot already, why not call it quits engine wise and save up till you can get a tjet or a mjet or something not fiat...
Click to expand...


I never said i spent a lot of money. Most expensive thing was the gsr induction.

Exhaust manifold cost me less that 15 pounds so i wouldn't call that expensive. Re-map can be done using usb in my case since i'm running an lpg conversion so that's free. My plan as regards cam was to drop in an A866 cam from a punto 75 for torque throughout rev range (that's again very cheap to do).

I do all the work on the car so labour cost is not an issue and the results are there. I have not been to a rr but it can beat a 1.4 8v without probs and keeps up with a 16v.

As regards the why i do it, it's called a hobby. I will soon be getting a giulietta 2.0 jtdm so it's really not a question of trying to be fast and cheap but the love of modifying cars and engines for personal satisfaction.

Maybe i'm not right in the head, but to me it feels better driving a 1.2 with a few mods i made myself, than paying big money to a garage and never touching a spanner yourself
 
chricol said:
I never said i spent a lot of money. Most expensive thing was the gsr induction.

Exhaust manifold cost me less that 15 pounds so i wouldn't call that expensive. Re-map can be done using usb in my case since i'm running an lpg conversion so that's free. My plan as regards cam was to drop in an A866 cam from a punto 75 for torque throughout rev range (that's again very cheap to do).

I do all the work on the car so labour cost is not an issue and the results are there. I have not been to a rr but it can beat a 1.4 8v without probs and keeps up with a 16v.

As regards the why i do it, it's called a hobby. I will soon be getting a giulietta 2.0 jtdm so it's really not a question of trying to be fast and cheap but the love of modifying cars and engines for personal satisfaction.

Maybe i'm not right in the head, but to me it feels better driving a 1.2 with a few mods i made myself, than paying big money to a garage and never touching a spanner yourself
Click to expand...

Sorry mate didn't want to seem as I was having a go. Sorry I read it wrong I thought u said u had spent (insert figure here) already that was all. Your like me. I do all the work my self to :)
 
We have an accord then mate ;)

(Of course i'm not referring to the car. I would never drive a rice burner hehe)
 
You must log in or register to reply here.

Similar threads

E
Technical Help needed failed mot on emissions so I buy a new cat will this fix my emissions
Replies
15
Views
975
GrandePunto PL
GrandePunto PL
AnthonyH
Technical Exhaust
2
Replies
26
Views
2K
AnthonyH
AnthonyH
I
Tuning Runs like sh*te after decat and turbo swap
Replies
8
Views
1K
SnuffRadu
SnuffRadu
O
Technical GRANDE PUNTO VAN 1.3 MJT Two questions
Replies
0
Views
359
Optikon
O
Y
Technical Down pipe after cat
Replies
0
Views
687
ycming
Y
Back
Top