RS2 cats max horsepower

[bertman]

What's the max horsepower that the RS2 cats can handle.My turbo is being re- built atm and the guy says that there has been an issue with back pressure or lack of it to be precise.
Thinking of 're installing the cats and keeping them on
My car is RS2+ spec

[saltinot]

It's always been my understanding that zero backpressure is optimal on a turbo car. Backpressure=lag and less HP.

[Error404]

Be interested to hear them qualify that reasoning

[bertman]

Something to do with the oil seals.It has been smoking at long periods of idle.It has gone to borg warner to be rebuilt and a small mod done to it which will stop this doing it in the future.MOT is coming out and i doubt it will pass the emissions with all that smoke coming out.
They asked whether I was running a bigger exhaust than standard,which I am with de-cat pipes.
So I cannot explain fully but that is what they said

[s2driveruk]

http://www.turbodynamics.co.uk/technical/technical-info/turbo-matching/other-factors-consider/exhaust-systems/

[bertman]

Well its not a 4" system,its a milltek RS2 cat back and RS2 downpipe,with de cat pipes.So there is logic in what they are saying then.
So will adding the cats back on provide a little bit more back pressure?

[s2driveruk]

yeah would appear to be even though i knew it wasn't a 'drainpipe' on yours

[Error404]

I don't buy it, the changes you've made are not that drastic.

[K Simmonds]

Yeah, I'm a little dubious myself, but without hearing their reasoning it's hard to be critical, as rule the least back pressure the better on turbo charged cars.

I've done 10K miles now on my RS2+ set up with a full 3" system all the way from the turbo to a single 2.75" Jetex back box and the turbo seems happy and spools up very early for a K24 7200.

Anyway to try and answer your original question. RS2 cat's are good for at least 350 BHP if not more as I know there's plenty of RS2's running generic 1.9/1.5 bar software with the cat's still in place without issue.

That said MTM felt it necessary to uprate them on their conversions once beyond 350/ 360 BHP according to any info I or anyone else on here can find. My MTM car has stock cat's which look a bit like a sports cat but with Audi part numbers on them, in fact I thought they were after-market until I had a good look at them. Mine has a K26/7 conversion and is a proper torque monster above 3K but I suspect it's peak power is a 'mere' 340BHP.

[diesel des]

If you have smoke at idle then it's not likely to be exhaust size related. Think about it. At idle exhaust flow is at minimum and even a 1 inch exhaust would cope with little back pressure. Check oil return hose. Check crank vent system. Check compression and valve stem seals. Likely to just be bad bearing in turbo causing the seals not to operate properly.

[AndyP]

Which company is it that's giving you this information??

[A80Avant]

I have run 420hp on rs2 cats and the back pressure was manageable

[bertman]

I have run 420hp on rs2 cats and the back pressure was manageable

Good to know mate