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Full decat or not?


Geezabloke

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Guest Martin F
Originally posted by Mid'lifecry'sis

Good thread, one of many on the subject...

 

I have left mine in due to conversation surrounding piston concerns after a while if they are both removed > I must find out why.. perhaps due to over boosting?

 

 

Where did you get that idea from ? That's the first time i have ever heard that removing the cats can affect your pistons ? :innocent:

 

Originally posted by Mid'lifecry'sis

In the mean time I have a GREDDY fuel cut defencer which is brand-new but is not programmable and therefore for those with electronic boosters in mind > aka another £1400! I'll take £75, was £95 new.

 

 

No FCD is programmable as far as i know. They are all adjustable but raise\remove the fuel cut in different fashions.

 

Can you tell me where you saw an electronic booster for £1400 ?

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Guest Martin F
Originally posted by ad500

Only while we were under the ramp did he notice that the front silencer pipe was in place but the internals had been removed giving no cats without the proper pipe.

 

This is either ingenious as you have effectively a straight through exhaust allowing easy connection of the rear cat once a year (passed MOT fine) or a total bodge.

 

Any opinions??

 

I take it you actually mean the front CAT ?

This is quite a popular mod with MKIII owners; to 'gut the CAT'. It's OK and it does the job but there is a question over the turbulence created by the exhaust gases entering a large empty chamber i.e. your old gutted CAT.

 

I think it's fair to say that it does the job but not quite as well as an appropriately formed suitable diameter pipe.

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Dave,

 

I have both cats out, VFCC and a Hiper back box.

 

As stated earlier in the post, I only got 0.91 bar with the above but, you can feel the difference straight away...:flame Dev You might be lucky and hit fuel cut at this stage but, mine did not.

 

I use my car everyday to goto work and it's fine, don't worry man!

 

You might want to get a boost gauge fitted ? not essential at this state but, you will need one next so, it might be good to get one fitted now.

 

Then it's time for a bleed valve or a electronic boost controller for some 1.2 bar fun :)

 

*************************

Ok, You asked for some guidance......

 

Re-read what Alex has stated on page one. As he says - it's tried and tested stuff.

 

If you are lucky, you will get around 1bar with a full decat and maybe on cold days hit fuel cut, that's why I fitted the VFCC at this stage but, didn't need it until I upped the boost later on to 1.2 bar.

 

HTH

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Originally posted by Martin F

Where did you get that idea from ? That's the first time i have ever heard that removing the cats can affect your pistons

 

Martin:

 

Graham Rudd's car was hitting 1.6 bar+ with both his cats out. He would have undoubtably holed a piston if left in that state.

 

 

ad500:

 

Is your car quite a late model?

 

Regards,

 

Nathan.

TDI PLC

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Jspec TT I have runs at 1 / 1.1 bar and fuel cut with a HKS Air and Hyper with first cat in... each engine to it's own... on a standard mild day. (new apexi gauge)

 

Colder plugs will raise my bar to 1.1 perminant I hope with missing and I believe that's where it seems to want to cut and go / peak now.... this is why I need a programmable defencer so that I know she will not go over 1.2, to much stress for standards so i hear and hey I don't need the change of injectors, resistors and pumps that DUDRSVR has gone through right now... etc...

 

Bleed valves are for people with brass bollo**! Cold day, gauge reads 1.3 say while your not looking, end result a thread on a the need for a new turbo or worse!!!!!!!

 

My next buy is from TRL.;)

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Option Motorsport Silverstone via MEC Cars my dealer told me about the pistons... Options are listed in,,,,urrrrr.... REVS mag, current issue within edit not adverts - known the top Jap guy there for a while and didn't realise he was a superstar jap race driver - knows a thing or 2 about Sup's.

 

Grasshopper near Manchester sell EBC's @£1400 I think, last quote 'ball park actually for fitting 2'....

 

I am toy'ing with the idea of first cat removal £100 (thanks for the offer) and the "adjustable" FCD £70.

 

170 squid and I will have 1.1/2 bar!

 

The sideways daily drive issues discussed here concern me.... Is it just a big kick at 4000rpm with gradual twins working up to that or given loss of back pressure re first CAT removal is there a loss from the T2 low down.? Loss of pressure due from CAT1 is grape vine stuff and could be crap?

Always willing to learne which may not mean I understand!LOL

:D

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Guest Martin F
Originally posted by Nathan

Martin:

 

Graham Rudd's car was hitting 1.6 bar+ with both his cats out. He would have undoubtably holed a piston if left in that state.

 

 

 

Hmmm, there's always one exception to the rule. :p

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And one exception not to be sniffed at either......

 

Theres been a few hitting 1.4 and even at that you are dicing IMO. Throw in a worn jap pump, manky stock IC and a full bore run and even the normally blowup-friendly stock ECU will have it's work cut out. Even if it can haul the ignition back enough to stop det the EGT's could take a piston out.

 

All I'm saying is, be careful. It's the owners that know very little about their cars and how they work who are the most suceptible. Graham was one of them.

 

Regards,

 

Nathan

TDI PLC

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Originally posted by Nathan

Martin:

 

ad500:

 

Is your car quite a late model?

 

Regards,

 

Nathan.

TDI PLC

 

No 1994 Uk 6spd. Anything I should be worried about? Seems to run perfectly at 1.0 or 1.4 bar.

 

I drive at 1.0bar 98% of the time

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