ncsu602

iTrader: (10)

1999 Z28, cam only car, ORY, Hooker catback. Just picked up a set of Thunderbolt ceramic cats to clean up the smell and pass a visual here in NC. I've been reading on here about the cats plugging up, coming apart, or glowing red hot due to a rich tune. I know that my tune is somewhere around 11.5:1 in the higher rpm range. Right now I've got an ORY and I love the way it sounds. I'm not as concerned about the smell, but my main concern is to pass a visual inspection. I'm considering gutting them before I weld them on just so I don't have to worry about them breaking up or glowing.

Do you think that if I put them on not gutted and being rich will they get too hot or plug up? How much will a gutted high flow cat change the tone over an ory? I'd rather have them on functional and cleaning up the smell (wife gets pissed since it's parked in the basement, smells up the house when I leave), but if nothing else I want to be able to pass a visual so I can take the car most places to be inspected rather than a select few. Thanks!

ShevrolayZ28

iTrader: (4)

Why not correct the AFR? There're more serious issues to worry about than glowing cats.

ncsu602

iTrader: (10)

Well, I bought the car as is. It was dyno tuned at a very reputable shop and was supposed to be a little on the rich side higher up in the rpms for safety. That number is what the previous owner said he thought it was. I'm in the process of getting all the info on the tune. I'm not too concerned about it right now since I drive the car about 10 miles every two weeks. I'm also considering doing some headwork and at that point I'd like to have it retuned anyway. I'm fairly new to tuning and am not sure what a good air fuel ratio is supposed to be.

garygnu

you would like to see a AFR of 12.9-13.0 for NA .

ncsu602

iTrader: (10)

Thanks for the replys......so assume the afr is normal or slightly rich throughout the rpm range and 11.5:1 up top, will this affect the cats? Anyone ever gutted a set of high flows?