Adding convertor (s). Yes, I said adding.

[SquareRoot]

I know my new Proflo efi is not emissions complient. However, I would like to clean up the exhaust smell as much as possible, mostly at idle.


No emissions, true dual exhaust. I am contemplating running dual, low restriction type catalitic convertors. I've got the space and they aren't that expensive.

What say y'all?

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[Big Chip]

I don't see why not. I've been contemplating doing the same to clean up the smell at idle. It's better than it was, but it's still got a rich smell that I can't get to go away.


I have to confess these are not my words. I copied and pasted from @DoubleDingo when he replied to you on the duplicate thread. All credit goes to him and I will bear all shame for my humor fail.

 

[Catbox]

My truck has them behind the 454 and it does not have a smell at all.
They do take the tone of the exhaust down quite a bit as well.
Even with the two chamber Flowmasters under it, the thing is pretty quiet unless you get into the secondaries...

When I end up redoing the whole system, I plan to run a new set of them as you have posted above.
I have to do the whole emissions testing thing every two years, so they have to be there.

 

[SquareRoot]

HTH did this thread post twice? Moderator.

 

[RoryH19]

I know my new Proflo efi is not emissions complient. However, I would like to clean up the exhaust smell as much as possible, mostly at idle.


No emissions, true dual exhaust. I am contemplating running dual, low restriction type catalitic convertors. I've got the space and they aren't that expensive.

What say y'all?

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I have those on my k5 with dual exhaust.
Have the metallic substrate version on a Camaro too.

 

[SquareRoot]

I have those on my k5 with dual exhaust.
Have the metallic substrate version on a Camaro too.

Did it eliminate the smell?

 

[RoryH19]

Did it eliminate the smell?

Yes. I first LS swapped my blazer it just had headers with no emissions. It was loud and smelled. Not as bad as a gen 1 SBC but definitely there.
These cats work well and I didn't notice any power loss. Also have magnaflow mufflers.

 

[SquareRoot]

Yes. I first LS swapped my blazer it just had headers with no emissions. It was loud and smelled. Not as bad as a gen 1 SBC but definitely there.
These cats work well and I didn't notice any power loss. Also have magnaflow mufflers.

Thank you sir! I'm going to look into them further and get r done.

 

[gotyourgoat]

Went with thunderbolt cats when I cut mine in. 3" spun, ceramic or metal core options. They fit the bill for what old brown needed at the time, happened to be the smaller/cheaper/convenient option as opposed to the others I was seeing when I was looking.
Compact design, high flow and at about 50 bux each to the doorstep they won out. A lot of online sellers have them(ebay, amazon, Walmart, etc) as well as direct.

Don't forget to add your tally to the list here..https://www.gmsquarebody.com/threads/catalytic-converters-does-your-square-have-them.28239/
Luckily I'm surrounded by garbage, found one of the boxes for them still on a shelf.

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[SirRobyn0]

Cats also make the exhaust less lung damaging, I have them on my truck, and I'd vote for it. The high flow cats, might slightly change the exhaust sound at higher RPM, but you shouldn't notice anything else other than less smell, oh and it might help your pipes last longer.

 

[80BrownK10]

Why are there two of these threads?

 

[SquareRoot]

Why are there two of these threads?

I asked the same question. I asked a mid to delete one of them.

 

[MikeB]

I'm no emissions expert here, but will cats have a shorter life if the A/F ratio is overly rich due to not having feedback from an O2 sensor? Then again, I don't think the auto manufacturers had any feedback when they started using cats back in the mid-1970s. The idea was to convert as much NOx and CO as possible to nitrogen, oxygen, carbon dioxide, and water.

***Edit: I just noticed the OP has EFI. But my question above is still a good one for a carburetor-equipped engine.

 

[SquareRoot]

So how do you decide on which size to use? With duals, I'll need two obviously but besides physical size it looks like they are classified by GVW.

Using two cats rated at 6000 lbs seems like overkill?

 

[Catbox]

I am simply choosing by pipe size.
I haven't look much farther than that when I am browsing the selections.