Cat without air pump damage?
 

I seem to remember reading a while back that running a cat that was designed for an airpump without an airpump was bad for the cat. I've searched and searched since then but cannot find any reference to this anymore.

Is running a cat that was designed to be used with an airpump (e.g. Bonez) without and airpump bad for it?

no... its fine. the air being injected is for dilution. i cant see how damage would come about from the air not being injected

Doesn't the pump help supply more oxygen to aid combustion in the cat? Without that the cat can clog.

page F-115 in the fsm only mentions dilution.

also, the air pump turns off around 3300rpm or something anyway. if that were the case then it would be on all the time. pretty sure combustion is over after it happens in the engine unless youre about that 2-step life :whip:

Most high flow cats can run fine without an air pump. I've run an SMB cat from Australia for 12 years or so now with no air pump.

If you want to pass emissions, you are going to need an air pump. If you just want to get the stink down, a high flow cat can help.

IMHO the air pump doesn't really have an impact on cat life - quality of the cat really affects that more so. I've seen cheap aftermarket cats last like a month before ejecting themselves.

Dale

Thanks for the replies. It's kinda funny really -- I actually have a working air pump, but the air connection pipe & silicon coupler that came with the Bonez are not currently installed. The silicon coupler that attaches directly to the inlet on the cat came off/burned off and the pipe started dragging on the road. I just removed the connection pipe until I could get a new pipe & coupler. This is the second time it has happened -- no sign of the coupler. Probably time for some stiffer motor mounts considering everything tranny-back is beefed up but the mounts are stock. I think motion of the motor must just be yaking it apart. :dunno:

https://cimg3.ibsrv.net/gimg/www.rx7...2e84894f65.jpg

FWIW...I’ve been running a Bonez cat with the airline removed AND premix at half rate AND with an OMP for over 13 years (~ 50k miles). No issues.

most of the time the air pump air is going to the exhaust ports, it only uses the split air pipe occasionally
https://cimg2.ibsrv.net/gimg/www.rx7...ab55cc26b0.png

The stock cat will clog and fail prematurely without an airpump. Its purpose is to inject additional air at lower rpms to increase the temperature and burn off pollutants. Some aftermarket cats like Bonez are designed so that they can be run without an air pump, but they still last longer with one.