If i am running that much power, will a 3.5 inch cat melt down? What if i happen to give it a 150 HP shot on top of that?

 

Hey, I go to MSOE too!...for a few more weeks until I go back home and try out something else instead.

The can't wont "melt down" just because you are running a lot of air through it. Its the overly rich conditions that ruin cats. As long as the engine has any kind of decent tune to keep it from spewing large amounts of raw fuel past the exhaust valves, your cat will survive. I guess the only concern would be whether a single 3.5" exhaust would be enough for that much power. I don't see it being much of a problem though since 3" exhausts are good to 400ish hp or so before they start limiting things quite a bit.

It'll be okay with the nitrous as well. You'll tend to want to run a tad on the rich side for safety when using spray, but it typically isn't used often enough during engine operation to cause a problem anyways.

 

But running a performance air-fuel ratio, not running overly rich like the factory sets it, could cause it over-heat, expecially when running nitrous, or don't you think so.

 

Cats are supposed to get hot. That's what makes them work effectively. They "melt" (or "clog") because raw fuel gets past the exhaust valves and essentially afterburns in the cat and ruins the elements in the cat.

 

Anyone know of a place where i can get a cat bigger than 3 inches? I think a 3in cat would be too restrictive behind that amount of air trying to go through it. Everyone talks about mandrel bent pipe, but if you have a cat, that is much more of a restriction than a little kink in the pipe. By the way, check your pm's duronclocker.

 

http://www.randomtechnology.com/products.html
They have universal cats in any size and they are not that restrictive.

 

I have one more question about this......

I have the SLP 1 3/4 headers with the slp y-pipe, it has 2 1/2 inch pipes that go into a 3 inch collector right before the endo of the y-pipe. I plan on cutting it right before the 3 inch section and attaching 2- 2 1/2 inch cats, one on each 2 1/2 inch pipe. From thereI am debting whether i will need more than a 3"mandrel bent pipe to my flowmaster muffler. I know one 3 1/2 inch pipe equals the area of two 2 1/2 inch pipes. But i think the dual cats would still be the biggest restrition. What do you guys think. Plus my current flowmaster 80 series muffler has 3 inch in and dual 2 1/2 inch pipes out.

 

Man I am in the same boat. I am building a Z28 that has a 383 and a T-56. It should put out 500 HP and I am also looking for the best route to go with pipes. I am going a different route that you for headers. I have a set of Hooker 2210 (coated). I plan to buy a bunch of oval pipe and oval spintechs I think and just route it all around as many things as possible. I am going to run dual 3.5" duals. At least that is plan A. I am def looking for a plan B, haha.

As for you, those cats are def going to be your biggest bottle neck. Even those 2 2.5" pipes are gonna look like staws compare to what the motor would need to operate at its optimal level.

I would say get it all up to 3" as fast as possible and let it get any smaller