Catalytic converter sizes: is bigger better?

[mugsee]

Would attaching a larger sized catalytic converter onto an exhaust provide better gains than a respectively smaller sized one?

Ie. with a 2.5" exhaust, would you net better gains if you attached an oversiezed 3" cat-converter and flared into the exhaust or a straight 2.5" cat converter?

[tinkerbell]

yes.

[mugsee]

Thanks!

[tinkerbell]

anytime!

[hebe]

Wow!

[rayDC2R]

I like the one word answers... LOL!
Question is... how much gain are we talking?

[BF]

I have no proof, but I'd think not much - given the difference between a cat and non cat isn't that great.

[j0nbubz]

agreed!

[tinkerbell]

I have no proof, but I'd think not much - given the difference between a cat and non cat isn't that great.

do you have proof of diff b/ween cat and non-cat?

[Wlee2]

im going to throw myself into the lions cage and say!

in mUgsees case its going to make jackall or No difference!!!

But under different Circumstances yes theres might be possible gains i think so =p.. But IMO still very little..

[mugsee]

You've gotta explain why it won't make a difference in my application and what my application is otherwise your response makes no sense. lol

For the others wondering, my initial question revolved around:
1) Would a bigger cat with larger catalytic conversion surface area (ie. inside the actual cat) be better over a cat with a smaller cat conversion area? (I assume the answer is yes)

The reason why I initially asked the question was because a lot of the cats that you see on the market nowadays seem to have different application sizes (ie. 2.25", 2.5", 3") and I was thinking about mating up an oversized 3" cat to a smaller 2.5" exhaust, thinking that a larger cat would naturally have a larger flow capacity however have come to realise that most of these cats have the same internals but just different flange ends, thus would probably all do the same job.

So, the question now becomes, will a cat with oversized flange ends (3" cat, 2.5" exhaust) with with the same internals be better than a cat with the same size flange (2.5" cat, 2.5" exhaust) as the rest of the setup?

[Wlee2]

You've gotta explain why it won't make a difference in my application and what my application is otherwise your response makes no sense. lol

For the others wondering, my initial question revolved around:
1) Would a bigger cat with larger catalytic conversion surface area (ie. inside the actual cat) be better over a cat with a smaller cat conversion area? (I assume the answer is yes)

The reason why I initially asked the question was because a lot of the cats that you see on the market nowadays seem to have different application sizes (ie. 2.25", 2.5", 3") and I was thinking about mating up an oversized 3" cat to a smaller 2.5" exhaust, thinking that a larger cat would naturally have a larger flow capacity however have come to realise that most of these cats have the same internals but just different flange ends, thus would probably all do the same job.

So, the question now becomes, will a cat with oversized flange ends (3" cat, 2.5" exhaust) with with the same internals be better than a cat with the same size flange (2.5" cat, 2.5" exhaust) as the rest of the setup?

seems to me he forgot some very important technical detail about who actually had to Drill that information into him.....haha

So, the question now becomes, will a cat with oversized flange ends (3" cat, 2.5" exhaust) with with the same internals be better than a cat with the same size flange (2.5" cat, 2.5" exhaust) as the rest of the setup?

IMO it just an oversized flange and prolly wont make a difference since its still flowing into a 2.5" section anyway.

lets assume the cat part.. is a set.. you cant change it. IT HAS to be there to meet requirements. so ignore the fact that its the exhaust most restrictive part. having said that now the 2.5" end attached to the 3" cat end will make no difference because the pipe will only flow as fast as your most restrictive section.. ignoring the cat offcourse =P

[tinkerbell]

wayne, please only post useful info...

the cat is the most restrictive part.

bigger is better. simple.

mugsee - metal substrate cat is way to go...

[Wlee2]

wayne, please only post useful info...

the cat is the most restrictive part.

bigger is better. simple.

mugsee - metal substrate cat is way to go...

umm did you not read mugsee post about the cat is the same body size? just diffrent flanges?

[TeMp]

Yes Wayne, stop randomly blabbering!

A thought came to me as I read all this. What happens to the air flow when it goes through to a 2.5 then 3 and then back to 2.5? Wouldn't you be getting some back pressure? I guess this would depend on shape and seeing most cats are curved, the air would just smoothely flow through the cat and just be bottled necked by the 2.5 again.

Seems like I have answered my own question!