Modified 1.8t sports cat????

[Vw nut]

Hi everyone currently modifying a MK4 aum 1.8t got a custom exhaust but was thinking about sticking a sports cat on it has anyone got any experience or advice about sports cat on the 1.8t ??? Cheers

[rottenegg]

I would avoid sports cats unless you want MOT headaches every year.

[Vw nut]

Sports cats are ok come mot time it's decat that won't pass a mot

[rottenegg]

Not necessarily. A sports cat on my 2007 GTI couldn't get CO below 0.2% at natural idle, which is the pass limit for that vehicle. The OEM cats measure 0.01%, for reference.

A lot of aftermarket sports cats are totally useless at the catalysing bit, and in all honesty, don't really reduce the flow restriction a whole lot either, compared to a straight pipe. I would do some research on ones that are known to pass on your car, or decat it and get friendly with an MOT tester!

[Vw nut]

Ok I see what you mean might give the Sports cat a miss thanks for the input mate

[GVK]

Quite amusing that you have a user called 'rotten egg' posting on a cat topic.

[Vw nut]

GVK said:

Quite amusing that you have a user called 'rotten egg' posting on a cat topic.

Haha like it

[Rodders2305]

also worth noting a sports cat will put the EML on unless you have it mapped out

[Vw nut]

Rodders2305 said:

also worth noting a sports cat will put the EML on unless you have it mapped out

OK cheers for the advice

[anonymous-user]

makes little difference and leaving cat is better for lag reduction.

[Vw nut]

Thesprucegoose said:

makes little difference and leaving cat is better for lag reduction.

OK cool really don't want to go de cat

[anonymous-user]

Vw nut said:

OK cool really don't want to go de cat

you may gain a few bhp, but cost v bhp increase makes little difference. turbo engines need back pressure to spool, so decat helps free flow higher up but lag lower down. Modding can be obsessive on details but better look at other areas to improve.

[Vw nut]

Thesprucegoose said:

Vw nut said:

OK cool really don't want to go de cat

you may gain a few bhp, but cost v bhp increase makes little difference. turbo engines need back pressure to spool, so decat helps free flow higher up but lag lower down. Modding can be obsessive on details but better look at other areas to improve.

Yes mate got a front mount bigger intake pipe induction kit straight though exhaust apart from the cat r8 coil pack forge 007 need to fit these parts then time for a remap

[anonymous-user]

what turbo? ko3 or ko3s

[Vw nut]

Ko3s aum

[anonymous-user]

seems 220-240 max, i would keep cat, and remove weight.

[Vw nut]

Thesprucegoose said:

seems 220-240 max, i would keep cat, and remove weight.

Remove weight that might not work just put a sub in the boot

[rottenegg]

Thesprucegoose said:

Vw nut said:

OK cool really don't want to go de cat

you may gain a few bhp, but cost v bhp increase makes little difference. turbo engines need back pressure to spool, so decat helps free flow higher up but lag lower down. Modding can be obsessive on details but better look at other areas to improve.

Turbo engines don't NEED back pressure and neither do they benefit from it. Same applies to n'asp engines.

Flow optimisation to get spent gases out as quickly as possible is what engines like. Back pressure does the exact opposite.

To give you an example of how brutal back pressure is, Audi had to change the exhaust valve springs on the 8P S3 because back pressure prevented the valves from fully closing at high rpm.

Everything downstream of the turbine wheel is a restriction. The only reason there is a cat in the downpipe, and another one under the car, is because Brussels mandated it. VAG didn't put them there to aid turbo spool.

I agree with you on focussing on other areas of the car. These cars have tiny little turbos anyway, so won't see big gains playing with cats etc.

[Vw nut]

Cheers mate thanks for the input