#1: de-cat. Author: bullous206, Location: broughton astley, leicesterPosted: Sun Mar 20, 2011 5:40 pm ---- anyone know how to de-cat an exhaust. ive got a 1.4 8v
cheers bullous206.
#2: Re: de-cat. Author: Lee, Location: EnglandPosted: Sun Mar 20, 2011 5:42 pm ---- Waste of time you'll lose power and you'll more than likely fail the mot
#3: Re: de-cat. Author: ukskater01, Location: sutton surrey/welwyn garden cityPosted: Sun Mar 20, 2011 5:42 pm ---- Cut cat out, weld pipe in. Well I think it something like that anyway!
#4: Re: de-cat. Author: bullous206, Location: broughton astley, leicesterPosted: Sun Mar 20, 2011 5:47 pm ----
Lee wrote:
Waste of time you'll lose power and you'll more than likely fail the mot
rekon? not too bothered about the mot its just had one lol, will i really lose power?
#5: Re: de-cat. Author: robdob, Location: oxfordPosted: Sun Mar 20, 2011 5:48 pm ---- nah u buy a straight pipe rather than cut out and weld (best option imo) if you cut it out and weld you will probs weld back on p**sed and it will be a b***h to mess about with. and lees right itll fail an mot... really not worth it tbh
#6: Re: de-cat. Author: Harry, Location: StaffordPosted: Sun Mar 20, 2011 5:48 pm ----
ukskater01 wrote:
Cut cat out, weld pipe in. Well I think it something like that anyway!
Exactly, pretty hard how to do a how as you have to know what you are doing. Or if you have a decat pipe ready to go on you could fit that. But it's a b*****d fitting into the centre pipe, as well as removing the old one + getting it to fit without gas leakage.
I have a de cat purely because my cat compltely broke and rattled with a fair while till the MOT and it was a lot cheaper / easier to fit and weld a pipe on and just fit a second hand cat for the MOT then change back again.
#7: Re: de-cat. Author: Antknee, Location: ManchesterPosted: Sun Mar 20, 2011 5:53 pm ----
bullous206 wrote:
Lee wrote:
Waste of time you'll lose power and you'll more than likely fail the mot
rekon? not too bothered about the mot its just had one lol, will i really lose power?
What about next year? lol
#8: Re: de-cat. Author: chris_rock206, Location: Belfast, Northern IrelandPosted: Sun Mar 20, 2011 5:57 pm ---- wat about a 4 branch manifold for a 1.4 8v i was thinkin of one lol
#9: Re: de-cat. Author: Lee, Location: EnglandPosted: Sun Mar 20, 2011 5:58 pm ---- An NA needs the backpressure from the CAT
#10: removed Author: shellis, Posted: Sun Mar 20, 2011 5:58 pm ---- removed Last edited by shellis on Sat Feb 04, 2012 10:51 am; edited 1 time in total
#11: Re: de-cat. Author: bullous206, Location: broughton astley, leicesterPosted: Sun Mar 20, 2011 5:58 pm ----
Harry wrote:
ukskater01 wrote:
Cut cat out, weld pipe in. Well I think it something like that anyway!
Exactly, pretty hard how to do a how as you have to know what you are doing. Or if you have a decat pipe ready to go on you could fit that. But it's a b*****d fitting into the centre pipe, as well as removing the old one + getting it to fit without gas leakage.
I have a de cat purely because my cat compltely broke and rattled with a fair while till the MOT and it was a lot cheaper / easier to fit and weld a pipe on and just fit a second hand cat for the MOT then change back again.
what did it sound like when you de-catted it?
#12: Re: de-cat. Author: bullous206, Location: broughton astley, leicesterPosted: Sun Mar 20, 2011 5:59 pm ----
Antknee wrote:
bullous206 wrote:
Lee wrote:
Waste of time you'll lose power and you'll more than likely fail the mot
rekon? not too bothered about the mot its just had one lol, will i really lose power?
What about next year? lol
ahha 106 gti!!!!!!
#13: Re: de-cat. Author: Jay794, Location: Sheffield/Chesterfield/DronfieldPosted: Sun Mar 20, 2011 6:12 pm ---- Unweld cat, reweld with straight pipe, done
#14: Re: de-cat. Author: Lewis1304, Location: NuneatonPosted: Sun Mar 20, 2011 6:13 pm ---- I have a decat and very happy with it.
"there's a lot of guff mumbled about backpressure, but what happens in a properly designed system is that the exhaust gas velocity is kept high enough to effectively 'pull' the last of the exhaust out of the cylinders and allow more clean air and fuel in for the next cycle.
If the pipe is too small, the exhaust gas won't be able to get out fast enough - think blowing through a straw - and the charge in the cylinder won't be cleared as well as it might.
If the pipe is too large, the exhaust gas will be travelling too slowly to create the 'pull'.
Trick is finding the balance between too large and too small. A catalytic converter will add resistance to flow, so a high flow sports cat or a decat with a correctly sized pipe can add a noticeable amount of power."
#15: Re: de-cat. Author: nakednakeddave, Location: aberdeenPosted: Sun Mar 20, 2011 6:41 pm ----
Lewis1304 wrote:
I have a decat and very happy with it.
"there's a lot of guff mumbled about backpressure, but what happens in a properly designed system is that the exhaust gas velocity is kept high enough to effectively 'pull' the last of the exhaust out of the cylinders and allow more clean air and fuel in for the next cycle.
If the pipe is too small, the exhaust gas won't be able to get out fast enough - think blowing through a straw - and the charge in the cylinder won't be cleared as well as it might.
If the pipe is too large, the exhaust gas will be travelling too slowly to create the 'pull'.
Trick is finding the balance between too large and too small. A catalytic converter will add resistance to flow, so a high flow sports cat or a decat with a correctly sized pipe can add a noticeable amount of power."
thats all very well, but by just putting in a decat, you ruin the way the exhaust is made to work, if its a whole system made for that purpose, then thats fair enough...
#16: Re: de-cat. Author: spike_202, Location: West midsPosted: Sun Mar 20, 2011 7:31 pm ---- Go for it mate they sound mint and you can feel the freeness/less restriction straight away. But it will make it v. Loud if you have a aftermarket back box. My de cat put around 10 bhp on my set up so can't see how they lower the power 2bf lol Last edited by spike_202 on Sun Mar 20, 2011 7:44 pm; edited 1 time in total
#17: Re: de-cat. Author: nakednakeddave, Location: aberdeenPosted: Sun Mar 20, 2011 7:32 pm ---- how do you know it added 10hp....? because they told you?
#18: Re: de-cat. Author: Big_Rich180, Posted: Mon Mar 21, 2011 4:19 am ---- Im with Lee on this one, I had a de-cat for my 180 and it sapped the torque from the engine....really not worth it save your money and buy a massive steak pie...in the long run you would be more happy with it.
#19: Re: de-cat. Author: Kersh, Location: Bridgnorth, Nr WolverhamptonPosted: Mon Mar 21, 2011 4:27 am ----
nakednakeddave wrote:
how do you know it added 10hp....? because they told you?
read his project lol
hes got a s**t load more air going in than anyone else so a decat is guaranteed to help flow in that situation.
cant see the benefit on a standard engine though without serious intake mods..
#20: Re: de-cat. Author: Harry, Location: StaffordPosted: Mon Mar 21, 2011 6:01 am ----
bullous206 wrote:
Harry wrote:
ukskater01 wrote:
Cut cat out, weld pipe in. Well I think it something like that anyway!
Exactly, pretty hard how to do a how as you have to know what you are doing. Or if you have a decat pipe ready to go on you could fit that. But it's a b*****d fitting into the centre pipe, as well as removing the old one + getting it to fit without gas leakage.
I have a de cat purely because my cat compltely broke and rattled with a fair while till the MOT and it was a lot cheaper / easier to fit and weld a pipe on and just fit a second hand cat for the MOT then change back again.
what did it sound like when you de-catted it?
It's deeper and a fair bit louder, I have a peco backbox and it was loud before, and now it's annoying loud. Also backfires quite a lot but it didn't with the standard backbox so it's probably a mix of the two.
#21: Re: de-cat. Author: MrBSI, Location: What's it to you? ? ?Posted: Mon Mar 21, 2011 2:01 pm ----
Lee wrote:
Waste of time you'll lose power and you'll more than likely fail the mot
It WILL fail the mot next year
Dont forget the famous
ANTIPOLLUTION FAULT
#22: Re: de-cat. Author: Addaz, Location: SuffolkPosted: Mon Mar 21, 2011 3:31 pm ---- Ive had mine on for around 5 years now, never failed the MOT
She is quiet and gains are good, compared to standard
But when you are concerned about back pressure, gimme a break its frigging 1.4
#23: Re: de-cat. Author: MrBSI, Location: What's it to you? ? ?Posted: Mon Mar 21, 2011 3:33 pm ----
Addaz wrote:
Ive had mine on for around 5 years now, never failed the MOT
Yet
#24: Re: de-cat. Author: Lewis1304, Location: NuneatonPosted: Mon Mar 21, 2011 3:50 pm ---- Decat is the way forward, I love the noise of mine now with it, it back fires, flames and sounds awesome, gives it a rawr. Ive noticed an increase in power... however it could be down to the manifold also.
Slip the MOT guy a tenner and im sure he will wheel in a nice 1.0 corsa for your emmisions tests
Slip the MOT guy a tenner and im sure he will wheel in a nice 1.0 corsa for your emmisions tests
Would have to be a total idiot to risk his mot license like that
People say it so casually, but I would feel like a knob trying that...
Because you are one.....
Love you lots
Oi you
ly2
I don't know how I would go around finding a garage to 'pass' it for me.
Do I already have to have exsisting friends?
If so, I'm f****d..
#30: Re: de-cat. Author: Lewis1304, Location: NuneatonPosted: Mon Mar 21, 2011 4:09 pm ---- Friends who work for garages yes or ask people who are in tuning car circles where to take it locally. I just take it same place my mates take their evo and ST's etc.
Slip the MOT guy a tenner and im sure he will wheel in a nice 1.0 corsa for your emmisions tests
Would have to be a total idiot to risk his mot license like that
28 days and you can apply for a new one, just open it up in a different name.
£70 will get you a MOT without the car/van even been in the garage
#32: Re: de-cat. Author: MrBSI, Location: What's it to you? ? ?Posted: Mon Mar 21, 2011 4:17 pm ---- About time the goverment took all mot testing in house
#33: Re: de-cat. Author: dwallace, Location: ShropshirePosted: Mon Mar 21, 2011 4:23 pm ---- Does a de-cat turn the engine management light on, my step son's cat is buggered and the enginge management light is on, if I went decat option how would I turn it off?
Does a de-cat turn the engine management light on, my step son's cat is buggered and the enginge management light is on, if I went decat option how would I turn it off?
Cheers
Darren
yes. because you will F*** up the O2 sensor after the cat.
#36: Re: de-cat. Author: Lewis1304, Location: NuneatonPosted: Mon Mar 21, 2011 4:43 pm ---- Get a Lambda Sleeve and a m18 plug for the manifold and reposition the lambda sensor elsewhere where it will detect oxygen. Plus wipe error codes and it should be fine
Lewis
#37: Re: de-cat. Author: D4NTP, Location: Not Leeds or its surrounding areas!Posted: Mon Mar 21, 2011 5:56 pm ----
Seabook wrote:
Lee wrote:
MrBSI wrote:
Lewis1304 wrote:
Slip the MOT guy a tenner and im sure he will wheel in a nice 1.0 corsa for your emmisions tests
Would have to be a total idiot to risk his mot license like that
28 days and you can apply for a new one, just open it up in a different name.
£70 will get you a MOT without the car/van even been in the garage
these MOT station are just great~!
I don't know about paying a tenner......the deal i get is, anything like that 'you did it after it left here, alright'.....must have a generous MOT'er
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not too bothered about the mot its just had one 
lol, will i really lose power?
