Turbo Owners Running Cats - Which Brand Holds Up?

[Cookiemonster]

Just as title states, I'm running a 2019 TT (M6) Hellion kit with header back exhaust no mufflers/resonators and holy shit does this car backfire and have fumes like I'm being waterboarded with gasoline (gasboarding?) anytime I'm idling or driving slowly.

I'm going to have some cats welded in but am looking to those of you running TT or ST setups, specifically, as we have the highest temps and want to make sure whatever brand cats I go with, they will hold up. So those of you who are running cats in your turbo setup, what brand are they

Also curious if you have pics to post or tell me where your cats are placed and if you have a noxious smell and backfires even with the cats on.

Thanks for your help, my forced induction brethren.

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[Barrel]

How much power are you running? Anything over 750rwhp you're gonna have cat failures IMO.

 

[Cookiemonster]

I'm not sure on power numbers, haven't dyno'd it yet. TBH I'm confused as to how power numbers and cat failures are correlated. There are many GT350/GT500s being modded to achieve well over 750rwhp and they aren't all ditching cats and having failures.

Everything I understand about failing cats on otherwise sound modded cars has to do with fuel mixture being too rich, where the catalyst actually melts due to fuel literally burning inside of the cat.

 

[Barrel]

My understanding is that it's not due to just a rich fuel mixture. Rather just too much in the exhaust stream overwhelming the cats. My cats (high-flow stainless works) began failing at under 800rwhp. I do race my car, so YMMV, but I've seen plenty of cars start to damage even aftermarket cats at the 750rwhp level.

Of course if you have E85 then switching fuels is really the best medicine. Better fuel and significantly lower fumes.

 

[engineermike]

Paging @GregO

 

[Andrew@Lethal]

Just as title states, I'm running a 2019 TT (M6) Hellion kit with header back exhaust no mufflers/resonators and holy shit does this car backfire and have fumes like I'm being waterboarded with gasoline (gasboarding?) anytime I'm idling or driving slowly.

I'm going to have some cats welded in but am looking to those of you running TT or ST setups, specifically, as we have the highest temps and want to make sure whatever brand cats I go with, they will hold up. So those of you who are running cats in your turbo setup, what brand are they

Also curious if you have pics to post or tell me where your cats are placed and if you have a noxious smell and backfires even with the cats on.

Thanks for your help, my forced induction brethren.

Kooks Green Cats all the way! We can get you set up here at https://www.lethalperformance.com/

 

[Cookiemonster]

My understanding is that it's not due to just a rich fuel mixture. Rather just too much in the exhaust stream overwhelming the cats. My cats (high-flow stainless works) began failing at under 800rwhp. I do race my car, so YMMV, but I've seen plenty of cars start to damage even aftermarket cats at the 750rwhp level.

Of course if you have E85 then switching fuels is really the best medicine. Better fuel and significantly lower fumes.

I wish we had more than 1 station within 30 miles of me that offered E85, then I would run it, but I can't drive 45 minutes away every time I need fuel or have to plan my trips around E85 stations...we're just not there yet in terms of E85 popularity at my location.

I gotta ask if everyone smells like exhaust until changing clothes and showering even after short drives with the windows up...because this car out of all the cars I've had with no cats, no resonators and 3"+ exhausts, is obscenely bad in the fumes department. I can turn the engine over and sit in the car for 2 minutes on warmup, get out, go in the house, and I'm fucked for the entire day unless I shower/change clothes.

If this is normal, why the hell do our cars fume up so much worse than other higher hp setups on say, I6 engines or even 4cyls? Is this something that can be alleviated?

 

[engineermike]

I’ve done a little looking into this and wondered about alternatives. HJS makes high performance elements. The interesting thing about the site is they are rated based on power level and note the inlet size vs power level:

https://www.hjs-motorsport.de/products/tuning/universal-catalysts.html

I’ve also kicked around the idea of buying take-off cats from something like a GT500.

 

[Bullitt69]

Cookie,

Hellion sells High Flow Cats as an option to their set ups, so I've ordered through them, hopefully they stand up to the abuse of 93 - yes E85 is probably the better option (Hear it smells good tooo), but I would like to take the car on trips later this summer so 93 / Octane Booster for now.

I haven't heard any <Bad> things about them, so it might be worth looking into.

Good Luck,

 

[Angrey]

I wish we had more than 1 station within 30 miles of me that offered E85, then I would run it, but I can't drive 45 minutes away every time I need fuel or have to plan my trips around E85 stations...we're just not there yet in terms of E85 popularity at my location.

I gotta ask if everyone smells like exhaust until changing clothes and showering even after short drives with the windows up...because this car out of all the cars I've had with no cats, no resonators and 3"+ exhausts, is obscenely bad in the fumes department. I can turn the engine over and sit in the car for 2 minutes on warmup, get out, go in the house, and I'm fucked for the entire day unless I shower/change clothes.

If this is normal, why the hell do our cars fume up so much worse than other higher hp setups on say, I6 engines or even 4cyls? Is this something that can be alleviated?

I've had catless 3" with LT's for quite some time now, about 3 or 4 months of it on a 93 tune and the rest of the time on a flex/dedicated E85 tune and never had what you're describing. I've had 3 mustangs over the yeas and all 3 I yanked the cats and I do remember getting some additional fume/smell but nothing like what you're experiencing. Unless you just have some bloodhound level smell, something seems off.

Have you checked for exhaust leaks?

 

[WildHorse]

My understanding is that it's not due to just a rich fuel mixture. Rather just too much in the exhaust stream overwhelming the cats.

Heat. No cats on a turbo car will survive even mild boost. It's not a matter of 'if', it's a matter of 'when'.

 

[Dominant1]

Boost = catless dont take the risk. My American racing headers high flow cats were toast a month after my Procharger D1x was installed. luckily i caught it before it could do any damage.yeah you can get used to the fumes, but you also get used to 25 extra hp.

 

[CompOrangeFanatic]

I just installed Gsport Gesi ultra high flow green cats on my car in preparation for going FI sometime in the very near future. These cats are supposed to handle up to 850HP per cat and temps up to 1700F. Look up Gesi cats on the web and you'll find out they're made for FI and race cars. I was able to find and get a pair for $700 shipped off Ebay. I have pics and part#'s if you want them. https://gsportbygesi.com/

 

[Dominant1]

Ive seen green cats fail. They just take longer to fail..cats with boost is like your nose with nose plugs, the pressure has to be released somewhere. When boosted its released in the destruction of the cat internals.

 

[CompOrangeFanatic]

Ive seen green cats fail. They just take longer to fail..cats with boost is like your nose with nose plugs, the pressure has to be released somewhere. When boosted its released in the destruction of the cat internals.

Gesi makes two versions, high flow and ultra high flow. I bought the ultra high flow ones that can handle higher temps. They're 300 cell cats. All I can say is read about them and to the OP...do your research. But these are the best ones I could find out there. These aren't the ones offered on Kooks systems I can tell you that.

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