#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...
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not too bothered about the mot its just had one 
lol, will i really lose power?
