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Model specific boards => Golf mk3 => Topic started by: stainesy on 07 November 2011, 17:16

Title: VR6 cat on an 8v?
Post by: stainesy on 07 November 2011, 17:16
Hi I was just wondering if a VR6 cat is the same fitnent as an 8v. I no you can put a vr6 exhaust on 8v from cat back as I have it on mine but will a VR5 cat fit strait on?
Title: Re: VR6 cat on an 8v?
Post by: tweed on 07 November 2011, 17:21
Some are different lengths I believe. but it will fit  :smiley:
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 07 November 2011, 17:27
Well Godzilla is giving me a full VR6 standered exhaust so I was going to replace mine with the cat middle pipe and middle box keeping my Sebring backbox. Will it be a strait swap them?
Title: Re: VR6 cat on an 8v?
Post by: VW BUSH on 07 November 2011, 17:29
I bought a one for my 8v was supposed to fit 8v/16v and Vr6, needed a quite bit of fitting before it would fit properly but it is a cheap sh!te copy.

I have a sport cat which I bought for £50, when I get five mins I am going to cut the flange and tubes of the old one and weld it together, hopefully I will be able to get the exhaust sitting right by doing this :lipsrsealed:
Title: Re: VR6 cat on an 8v?
Post by: Khare on 07 November 2011, 17:41
Thought 8v had 2.25" bore and 16v/VR6 had 2.5"?
Title: Re: VR6 cat on an 8v?
Post by: dom on 07 November 2011, 17:47
Thought 8v had 2.25" bore and 16v/VR6 had 2.5"?

They're all the same when they leave the cat, the 8v reduces between cat and silencer :wink:
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 07 November 2011, 17:55
Ok so is it a strait swap or not?
Title: Re: VR6 cat on an 8v?
Post by: tweed on 08 November 2011, 15:41
Well Godzilla is giving me a full VR6 standered exhaust so I was going to replace mine with the cat middle pipe and middle box keeping my Sebring backbox. Will it be a strait swap them?

if the sebring backbox was made for a 8v gti (50mm) no it won't fit.
if it's a 16v/vr6 backbox (55mm) it will.

But the sebring backbox may not fit a standard exhaust due to the bending and where the two join together.
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 08 November 2011, 15:59
I no about the size differences in exhaust as my Sebring cat back is from a VR6.
What I want to no is will a VR6 cat fit my 8v.
Not bothered about the rest as I no all that is ok. 
Just need to no if the cat from a VR6 will fit strait on my 8v.
Title: Re: VR6 cat on an 8v?
Post by: Len on 08 November 2011, 16:02
Think it will be a hold up against and see as length maybe an issue too!
You may also like to think if the VR6 one is to manly for the 8v and may restrict flow!
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 08 November 2011, 16:14
Not to bothered if the cat is longer as can just cut the centre pipe down to sort it. Was mainly asking if the bolt on area with 3 bolts that bolts to down pipe is the same.
You recon the VR6 cat will be more compact inside?
Title: Re: VR6 cat on an 8v?
Post by: Len on 08 November 2011, 16:16
Well it is designed and matched to a much more powerful engine so may cause flow problems is all I'm saying.
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 08 November 2011, 16:27
Yeah I see what you are saying and you are right mate.
Just realised it don't matter if it is the shorter cat anyway as I I have the full system and will be replacing the cat, middle pipe and middle box so will have the longer middle pipe anyway.
Now just worried about the flow as you say it may be more restrictive.

Anybody on here no if it is or not?
Title: Re: VR6 cat on an 8v?
Post by: tweed on 08 November 2011, 17:17
will not be any different from a 8v cat  :wink:
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 08 November 2011, 17:33
will not be any different from a 8v cat  :wink:

Well as long as your sure. Nice1 cheers buddy. Hopefully loosing the huge Sebring middle box and replacing with standered VR6 one will give it a bit more of a roar.
Title: Re: VR6 cat on an 8v?
Post by: tweed on 08 November 2011, 17:44
If anything the cat will be bigger. flow rates will be the same.
inside the cat is a honeycomb shape with elements etc inside to burn the unburnt fuel. It won't be more "dense".


Title: Re: VR6 cat on an 8v?
Post by: stainesy on 08 November 2011, 18:01
Sweet. Yeah it platinum inside ain't it. My cat I have on at the mo has a hole hammered through the core. As my car kept heating up underneath where cat is so I made a hole to release pressure.
Title: Re: VR6 cat on an 8v?
Post by: tweed on 08 November 2011, 18:11
 :grin: :grin:

sounds like a old bloked cat?

I remember you only getting the problem after changing you exhaust?
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 08 November 2011, 20:42
:grin: :grin:

sounds like a old bloked cat?

I remember you only getting the problem after changing you exhaust?

Yeah that's right.
When I fitted the Sebring I kept getting very hot floor.
I still get very hot under back seats coz the Sebring middle box is huge that why I'm replacing with standered VR6 cat back to backbox.
Title: Re: VR6 cat on an 8v?
Post by: boneybradley on 08 November 2011, 20:51
the big issue is the connection and any bend from the manifold connection side.... the vr is very different there! It wont fit! (have a look at the connections between a vr6 manifold to cat and the one on an 8v)

from the cat back they are all the same bore (they use different connector (short) pipes
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 08 November 2011, 21:53
the big issue is the connection and any bend from the manifold connection side.... the vr is very different there! It wont fit! (have a look at the connections between a vr6 manifold to cat and the one on an 8v)

from the cat back they are all the same bore (they use different connector (short) pipes

thats what i have asked.
so the flange from cat to down pipe is diferant on the vr6 to the 8v then?
Title: Re: VR6 cat on an 8v?
Post by: boneybradley on 08 November 2011, 23:55

thats what i have asked.
so the flange from cat to down pipe is diferant on the vr6 to the 8v then?

yep I'm 100% sure
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 09 November 2011, 06:39

thats what i have asked.
so the flange from cat to down pipe is diferant on the vr6 to the 8v then?

yep I'm 100% sure

Ah bugger.
Title: Re: VR6 cat on an 8v?
Post by: tweed on 09 November 2011, 17:19
how is it different?
Title: Re: VR6 cat on an 8v?
Post by: boneybradley on 09 November 2011, 17:39
The connection is different (size or located differently or both?)

http://www.catalogue.bosal.com/pages/exh_system_list.php?query_nr=6&make=VOLKSWAGEN&model=Golf+III&body=Hatchback&cartype=&fuel=B&year=1996 (http://www.catalogue.bosal.com/pages/exh_system_list.php?query_nr=6&make=VOLKSWAGEN&model=Golf+III&body=Hatchback&cartype=&fuel=B&year=1996)
Title: Re: VR6 cat on an 8v?
Post by: tweed on 09 November 2011, 17:55
8v and vr6 look the same (well have the same numbers lol) the 16v looks different in that pic. And you can also buy a decat pipe that is for 8v 16v and vr6.

Last thing I want is to give someone bad advise but to me it looks fine.
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 09 November 2011, 18:02
Why does the 16v have the sleeve after the cat like the 8v when I don't really need it?
The 16v has the same size exhaust as the VR6 so really it don't need the sleeve.
I no the 8v needs it to reduce but it seems pointless on the 16v.

So what you recon people will it fit or not? Looks the same me.
Title: Re: VR6 cat on an 8v?
Post by: boneybradley on 09 November 2011, 18:38
All I can say is try it..... I am trying to find some vr6 cat photo's but seem to be failing! If I read correct it's the front flange which means the cat will sit more sideways on an 8v (which won't bother a decat)

b.t.w ignore the sleeve bit as some makers don't use them (bosal do to make the exhaust fit better as o.e was 1 piece and they all get cut differently!!)
Title: Re: VR6 cat on an 8v?
Post by: tweed on 09 November 2011, 18:39
And as I said the converter part of the cat is longer (not the pipe) so emissions will be low  :smiley:
Title: Re: VR6 cat on an 8v?
Post by: stainesy on 09 November 2011, 19:32
And as I said the converter part of the cat is longer (not the pipe) so emissions will be low  :smiley:

sweet.  :grin:

cheers guys i will let you all now when i go to change it all if it fits or not..
Title: Re: VR6 cat on an 8v?
Post by: tweed on 09 November 2011, 19:35
Fingers crossed  :lipsrsealed: