MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: AndyBrown on March 05, 2015, 10:58:59 am

Title: Decat and mot
Post by: AndyBrown on March 05, 2015, 10:58:59 am

Need a bit of advice please, I've tried searching but can't find what I'm looking for.

I'm going to take part in the group buy for BCS for a cat back and the loon to get downpipe and decay in a few month time.
Now I'm aware hat a decaf will cause an mot failure due to emissions but what's the solution to the problem, apart from a friendly mot tester.

I've seen the Eurojet has a vband system so you can fairly easy swap the decat to a sports cat but what's the solution for other downpipes?

Thanks

Title: Re: Decat and mot
Post by: rich83 on March 05, 2015, 11:09:14 am

Nige could make one for you that is modular so you an take the cat off... but its gonna cost you.

Title: Re: Decat and mot
Post by: xjay1337 on March 05, 2015, 11:24:53 am

MOT car. Fit decat next day.
Easy.

Title: Re: Decat and mot
Post by: AndyBrown on March 05, 2015, 11:27:44 am

I was thinking of BCS cat back and eurojet downpipe, but will there be any difficulty joint them?

Quote from: xjay1337 on March 05, 2015, 11:24:53 am

MOT car. Fit decat next day.
Easy.

What about the following year tho? Keep standard downpipe and refit it again?
Need to find myself a relaxed MOT place lol

Title: Re: Decat and mot
Post by: Powervalve Nige on March 05, 2015, 01:17:05 pm

Back in the early days Sports cats were small and inefficient in terms of volume throughput and emissions.
our cat has a 125mm cross section with a 77% open area in pure maths terms this equates to a ratio of over 90mm of flow, even allowing for the friction and drag coefficient the laminer flow will more than equate to a cat delete, thereby negating the need for a de cat unless for purely economic reasons.  :happy2:
Cheers
Nige

Title: Re: Decat and mot
Post by: xjay1337 on March 05, 2015, 02:22:43 pm

Just find a Ford Fiesta and stick the pipe up there. The first time is a pain (things get stuck and snap) but if you've put hi temp anti seize on everything when you put it together, you can drop the whole downpipe in about 15 minutes.

Nige I have always wondered about sports cats passing an MOT. So you're saying on your system at least, there's no benefit to having a de-cat for performance? And what about passing MOT's.

Title: Re: Decat and mot
Post by: Powervalve Nige on March 05, 2015, 04:13:27 pm

The key is the pm coating - we coat with 30grms which should be good for 8-10 years, and ours sails through an MOT.
Theoretically a  cat will pass with 5grms of PM - but the problem is with entropy the coating degrades to the point where it will not pass usually after 2-3 years.
The maxim is if the cat DP is cheap then the PM loadout is low - they are called precious metals because thats what they are, and they are expensive.
Cheers
Nige

Title: Re: Decat and mot
Post by: rich83 on March 05, 2015, 04:15:27 pm

Platinum?

Title: Re: Decat and mot
Post by: Powervalve Nige on March 05, 2015, 04:31:05 pm

platinum (Pt), palladium (Pd), and rhodium (Rh)  :party:

Title: Re: Decat and mot
Post by: rich83 on March 05, 2015, 11:32:21 pm

It would be quite cool if you posted photos of the internal of your exhausts  :party: Cats and Silencers.... put it in the showcase section.  :happy2:

Title: Re: Decat and mot
Post by: 56OctyVRS on March 06, 2015, 02:09:11 am

My 200 cel BCS motorsport cat sailed through the MOT and still is with its new owner.

Title: Re: Decat and mot
Post by: th3_f15t on March 07, 2015, 10:25:03 pm

For the minor increases in performance with a decat system over a sport cat system being over shadowed by the yearly job of refitting a stock exhaust just for a day, in my mind, makes it a no brained to get a sports cat

Title: Re: Decat and mot
Post by: Markweir12 on March 07, 2015, 11:00:19 pm

Mine will be for sale at end of month  :happy2: