[airtroop01]

Originally Posted by hawk02

Please explain how unburned fuel in the exhaust makes the cats run hotter? I thought the whole point of the cat over temp (COT) protection in the stock tune is to add more fuel and thereby make the engine run really rich to help cool the cats. No question detonation will overheat the cats but unburned fuel? What am I missing here?

You are correct in that the whole point of the cat over temp in the tune is to add more fuel and it cools the cats. It’s a common misconception that cats burn up due to going richer. However there’s a limit to this thinking:

When the gasses are leaving the heads they are at their hottest point let’s assume 1200* (that’s where combustion is happening) or so as they get some distance away the gasses cool down. Within the cat they reach about maybe 900-1000* - assuming the system is not plugged and things are flowing properly quenching cylinder temps with more fuel will reduce the exhaust gas temperatures and save cats.

If the cats are plugged and you have some restrictions due to previous over temp situations, the problem can get worse and that’s where cat temps can get to like 2000* as the restriction builds and more fuel is added thus melting the material further.

So, if you stay on top of it in the first place, you’re in good shape. You get out of balance and you’re making it worse and will need to swap the cat out.

[clg82]

Originally Posted by airtroop01

Magnuson 2650, toohighpsi fuel injection plates, cordes low side, RotoFab big gulp, 103mm snout and NW TB… Borla catback… and e85.

Similar setup to what Mike at Toohighpsi is running but he is pushing 900rwhp through the cats on his z06 if I recall correctly.

Mine is street driven 99% of the time with the occasional open track session if it works out with my schedule. Short distance to work but flogged daily on a few areas on my route so it’s not babied at all. I have not yet track tested the new setup as I planned to fine tune some manners with my tuner but I have not had enough runway to do that here without cars in the way.

If it wasn’t a pain in my state, I would run long tubes, high flow cats and a pair of resonators to keep the noise down some so street driving and having people in my car (work) isn’t a pain. I still may go that route but for now I am going to get there with this setup as it’s working out exactly as I hoped.

Holy hell man, well i guess that answers the question about what the stock cats can tolerate!!!

[Wuiquen]

Outside of the Kooks Gen 2, all other systems use hi flow cats that are shared with the SS. Some people have no issues while other do. Is this related to power and tuning? Tracking the car versus wknd driver?

What i really want to know for my case is will i be ok with the AR high flow cats (i think those are shared with the SS) given i will stay close to OEM power?

Additionally, would there be any other brand of high flow cats that i could try to use? The SC rated Kooks Gen 2 are about 700 a cat. The catted elbow section from AR is about $600 shipped.

[ST1LE]

Originally Posted by Wuiquen

Outside of the Kooks Gen 2, all other systems use hi flow cats that are shared with the SS. Some people have no issues while other do. Is this related to power and tuning? Tracking the car versus wknd driver?

What i really want to know for my case is will i be ok with the AR high flow cats (i think those are shared with the SS) given i will stay close to OEM power?

Additionally, would there be any other brand of high flow cats that i could try to use? The SC rated Kooks Gen 2 are about 700 a cat. The catted elbow section from AR is about $600 shipped.

I am in the same boat as you, wanting to add headers and high flows to my future ZL1.

The sticker shock sucks, but I dont think there is anything out there that has proven to work other than the Gen 2 Kooks cats.

I would rather buy once, even at a higher initial cost, than have to burn my money on cats(pun intended).

[Camaro1973]

Originally Posted by Wuiquen

Outside of the Kooks Gen 2, all other systems use hi flow cats that are shared with the SS. Some people have no issues while other do. Is this related to power and tuning? Tracking the car versus wknd driver?

What i really want to know for my case is will i be ok with the AR high flow cats (i think those are shared with the SS) given i will stay close to OEM power?

Additionally, would there be any other brand of high flow cats that i could try to use? The SC rated Kooks Gen 2 are about 700 a cat. The catted elbow section from AR is about $600 shipped.

I believe the gen 1 gesi cats were improved slightly to 500 hp per bank. A lot of high flow cats are only 200 cell. Really no point in using these tbh. The gesi gen 1 are 300 cell, gesi gen 2 are 400 cell, but gen 2 are larger cats and epa certified.

The design of the gen 1 cats is the problem. I don’t track my car, all 3 sets fouled with “spirited” street driving.

[Wuiquen]

Originally Posted by ST1LE

I am in the same boat as you, wanting to add headers and high flows to my future ZL1.

The sticker shock sucks, but I dont think there is anything out there that has proven to work other than the Gen 2 Kooks cats.

I would rather buy once, even at a higher initial cost, than have to burn my money on cats(pun intended).

Yeah i agree. This is why I am trying to figure out the best way to go about this.
It is irritating some what because some people have no problems while others do. Personally I would rather get the catted connections from AR so it's to fit the system but who knows what type of hi flow cat those are given those re shared across all V8s in the Camaro lineup

[Wuiquen]

Originally Posted by Camaro1973

I believe the gen 1 gesi cats were improved slightly to 500 hp per bank. A lot of high flow cats are only 200 cell. Really no point in using these tbh. The gesi gen 1 are 300 cell, gesi gen 2 are 400 cell, but gen 2 are larger cats and epa certified.

The design of the gen 1 cats is the problem. I don’t track my car, all 3 sets fouled with “spirited” street driving.

Yeah i have been researching the GESI. Is your latest set the UHO model? That shows it can handle up to 850 HP per cat.

I figured 500HP Gen 1 would be acceptable. It appears GEN1 is also offer in an EPA certified model.

Why would the model year of the car matter? It shows GEN1 for up to 2016 and then Gen 2 for newer. Is this for their marketing?

[Camaro1973]

Originally Posted by Wuiquen

Yeah i have been researching the GESI. Is your latest set the UHO model? That shows it can handle up to 850 HP per cat.

I figured 500HP Gen 1 would be acceptable. It appears GEN1 is also offer in an EPA certified model.

Why would the model year of the car matter? It shows GEN1 for up to 2016 and then Gen 2 for newer. Is this for their marketing?

Yes 850 per bank 4.5” size.

It’s marketing , 2016+ emissions were updated so the gesi gen 2 cats conform to those new specifications.

Gen 1 should hold up if your not making much boost. A lot of places are actually marking the gen 1 for non boosted applications.

If your making 700+ I would not use gen 1

[6spdhyperblue]

Originally Posted by Camaro1973

Yes 850 per bank 4.5” size.

It’s marketing , 2016+ emissions were updated so the gesi gen 2 cats conform to those new specifications.

Gen 1 should hold up if your not making much boost. A lot of places are actually marking the gen 1 for non boosted applications.

If your making 700+ I would not use gen 1

Do you have COT on or off in your tune?

[Camaro1973]

Originally Posted by 6spdhyperblue

Do you have COT on or off in your tune?

On, but it rarely every comes on.