My friend has a 94 Formula LT1. One of the previous owners added headers and removed the cat. He would like to put a cat back on and has the air pump in a box. I understand that the air pump originally went into the exhaust manifold, but these aftermarket headers do not have a place to attach. While looking at cats I see that some come with air inlet hoses and some do not. If he were to get one with an air inlet hose and reroute the air pump directly to the cat, would it have the same effect as the stock setup, or am I missing something? The air pump runs for a few minutes on startup to get the cat up to temp so it works faster, so would this do that or is the air inlet on a cat for something else? If this would not work, would adding a more modern cat solve the problem? Any suggestions are appreciated.

fswalt

 

What exactly is the "problem" you're trying to solve? All you will get out of hooking the air pump back up is a warm fuzzy feeling knowing your cat is operating a little more efficiently on a cold engine. Once it warms up, it makes no difference to the cat, and it doesn't affect engine performance one way or the other. My 3rd gen had the 2 manifold air injectors, in addition to a line to the cat. I would imagine having just the small air line to the cat wouldn't be nearly as effective, considering how much less air volume there is compared to 2 larger exhaust manifold injectors.

 

if your trying to pass emmissions, it has to be the same as stock. i guess it would depend on what state and how much they check.

 

He's just trying to get the car back into compliance as best he can. He's not going to rip everything off and put it back to stock, and they don't test in his state. Since he's putting the cat back on anyway, he just wanted to know how to make it work properly.

I guess a followup question would be, why does the universal cat from flowmaster have an air house to the cat when I don't think the original did. Maybe they use one model number for many different applications? I know the suggested unit from magnaflow does not have air inlet house on the cat.

fswalt