MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: berg on December 03, 2012, 09:55:10 am

Title: What does the pre-cat actually do?
Post by: berg on December 03, 2012, 09:55:10 am
With quite a few topics on people removing them to free up a bit more power/more noise but not affecting the MOT on emissions, what is the actual point of a pre-cat? What are they made out of as seen a photo of one smashed, they look ceramic almost?

Title: Re: What does the pre-cat actually do?
Post by: blackmagic on December 03, 2012, 10:34:31 am
It's for when the car is cold. The precast warms up a lot quicker. Both because of its finer construction and location to turbo.
So the car is that bit better on overal emissions. I guess if you were really unlucky and you at the mot place and engine was cold. You'd parked it there for some reason and they immediately tested it!
In reality this isn't going to happened.
Mine passes fine with my aftermarket cat / no pre cat.
Title: Re: What does the pre-cat actually do?
Post by: GrayMK5GTI on December 03, 2012, 12:56:15 pm
As BLACKMAGIC said ^^

IIRC, it is mentioned in my thread "Pre-cat. . . . .Removed! " also  :happy2:

Milltek and other aftermarket systems dont have one so there is no harm at all in removing it.
Title: Re: What does the pre-cat actually do?
Post by: sub39h on December 03, 2012, 05:13:10 pm
it's a requirement in Germany where they test cold emissions. it basically means your car won't be legal to run in Germany, if that's an issue
Title: Re: What does the pre-cat actually do?
Post by: GrayMK5GTI on December 03, 2012, 05:50:13 pm
That means anyone with an aftermarket TBE can't run in Germany, surely??  :confused:
Title: Re: What does the pre-cat actually do?
Post by: sub39h on December 03, 2012, 06:01:49 pm
Quote from: GrayMK5GTI on December 03, 2012, 05:50:13 pm
That means anyone with an aftermarket TBE can't run in Germany, surely??  :confused:

as far as i'm aware that may actually be correct - a member of one of the Audi forums i'm a member of mentioned this. he seemed quite clued up and spent a lot of his time there so i took his word for it
Title: Re: What does the pre-cat actually do?
Post by: zerolag on December 03, 2012, 07:03:39 pm
^^ mad.

Maybe if the UK plumits into a mini ICE age they will start us on that... mind you we'd have such nice cold air feeding our engines I wouldn't care.  :driver: