High Flow Cat or No Cat?
 

I am going to be getting a custom exhaust built for my 87 Iroc. I am going to go with a single 3 inch into a hooker aero chamber muffler with two 2 1/2 tailpipes. Should I go with a high flow cat or just delete the cat completely?

What are your experiences and opinions on this?

Re: High Flow Cat or No Cat?
 

First thing to consider is your displacement..........~6.3L and you are boosted so actual amount of gases exiting the engine will be 6.3L plus boost. So, that being said, you will be at the ragged edge of the capacity for a single 3' Hi-Flo Cat(most are rated at around 6L). thats before you put any boost in the motor. So....unless you are able to run one off of EACH bank of the motor......it will be a bottleneck.

Second thing to consider is SMOG NAZI's...........if you have no inspections where you live you are best off to go without.

Personally......I am going to go with one at each collector when I get the 427sb in......just to make a point.......I personally believe that the power loss will be so small that I may as well make the effort to save some fresh air for my Grankiz Grankidz.....you know what i mean????

Re: High Flow Cat or No Cat?
 

I have inspections where I live, but I work at a shop, so someone there will pass it for me. I think I am going to go with no cat. Is a single 3 inch plenty of flow for a 383 stroker with boost or should I go 4 inch exhaust?

Re: High Flow Cat or No Cat?
 

I have dual magnaflows and they have not hurt any performance, at leas that I can tell. Worth it in my opinion.

Re: High Flow Cat or No Cat?
 

Dual magnaflow cats?

Re: High Flow Cat or No Cat?
 

Yes Dual.
The issue is that you have not said what headers or routing you will be doing with the custom exhaust. I have shorties that go into 3" collectors/ypipe with dual cats into a single 3" flowmaster. I am using the stock routing. Cats I used are these:
http://www.magnaflow.com/02catalytic...niversal=59959

Re: High Flow Cat or No Cat?
 

I have Edelbrock shorty headers on it now. I think Mrbrooks had a good point, with mine being supercharged and a 383 stroker, I might be better off without a cat.

3.5 or bigger mandrel bent
Or dual 2.5

Re: High Flow Cat or No Cat?
 

I agree to a point. What is the loss going to be? 10hp?
I think the shorties are more of a restriction than dual cats will be. Unless they are 1 3/4, but I dont think Edelbrock makes them that large.

Re: High Flow Cat or No Cat?
 

Use the high flow cats. Car Craft did an article a few years ago, when Frieburger was still the editor and the logo was "Do It Yourself Performance" or something to that effect. Either way, their dyno mule lost 1 hp to dual high flow cats.

Re: High Flow Cat or No Cat?
 

Your best bet all the way around will be to send a PM to DYNO DON. Ask him what he can do that will be adequate for your application. He is making the ONLY shorty header i would even consider running on a blown stroker. You will have to put out a little more $$ for his pipes..........but in the end you cant beat them in the world of shorties.......I would think he can most likely do something custom to in the Y-pipe to make it a dual cat set-up that will be adequate......

Re: High Flow Cat or No Cat?
 

Thanks for the input everyone. I will post pics once I get it done.

Re: High Flow Cat or No Cat?
 

Agreed. Single 3" is certainly the bare minimum for this kind of displacement + FI

Re: High Flow Cat or No Cat?
 

Do they make headers with 3.5 Y-pipes or would I just have to get an adaptor? Will full size headers fit in a thirdgen camaro?

Re: High Flow Cat or No Cat?
 

http://www.summitracing.com/parts/do...t/model/camaro
or
http://www.edquay.com/camaro/index.html

best option will be the Ed Quay.......1 7/8 primaries at your displacement and blown the huge tube option will be best.....lol
will be a FULL custom Y-pipe to I and out the back....... 3"Y to merge and 4" out the back thru a Hooker Max Flow........ would be the best way to go....IMHO....

http://www.jegs.com/i/Hooker+Headers/520/21609/10002/-1
http://www.jegs.com/i/Flowmaster/389...oductId=744773

Re: High Flow Cat or No Cat?
 

Ok. Thanks.