Has anyone ever tried running double catalatic converters? Do you think it'll pass the tail pipe test? I figure, if one is able to do it... then adding another will only make the exhaust cleaner... I can't think of anything wrong with having 2 cats under there...

Any thoughts?

 

It better pass a smog check with two cats.

 

sounds like a good idea to pass. i couldnt think of anything wrong with it.

 

what a cat does is use heat to combine 2 molicules and make something different, So when It comes out of the first cat it is already gone through the process, Put it through another cat and nothing will happen. If it was that easy dont you think that every car out there would come stock with 2 cats... Dont waste your time...

 

make sure it gets warm so the second one will light off, or you might clog the second one up faster from not running it at operating temp.

IDK though, im more for elimitating emmisions equipment :D

-Dustin

[edit in reply to above post]
Chemical reactions take time, and there is limited time in the first cat, so the second may provide more. And some cars do come with 2 or more cats in series.
[/edit]

 

you wont be giving it more time though because by time it gets to the second cat it wont be combining the same molicules... And some cars still come with DPFI, doesnt mean its better or even makes sence

 

i think what hes thinking about is cars that run real rich with big cams. those cars may not pass with one, but if u run 2 cats close to the exhaust manifold/header, then it may work. this is the same idea that the wrx operates under. it has 3 cats. 01-02 audi s4 had 4 cats.

-spenc

 

[QUOTE=krustindumm]make sure it gets warm so the second one will light off, or you might clog the second one up faster from not running it at operating temp.

What could happen if the second cat clogs up? My engine won't choke would it? I figure, even if it doesn't heat up that much, exhaust would still flow through it... and it won't do any harm.

Thanks for the replies guys....

 

It takes time for it to clog, but it's the honeycomb struture inside breaking down that clogs it. If it gets VERY clogged then it will start making lots of backpressure and will cause the engine to run terrible since the exhaust will be so overly restricted. I had one clog up and the absolute fastest the car would go was 35 mph with the pedal mashed to the floor.

EDIT: running rich and running lean both kill cats. Running lean is actually worse.

 

my B16 was failing miserably with high flow cats. (duh.) i threw in 2 cats from an 03 mustang's H-pipe at my shop, quick passed in 15 seconds.

 

nothing wrong w/ runnin 2 cats... Rx7's have a precat and main cat becaust they put out so much emmions.

as for the comment about running 2 cats not doing any good, cats dont work 100% all the time.. if the first one misses some of it the secod will hopefully get the rest.

 

Hell, some lincoln mark viii have 5, 2 per header then they both run into 1 more....more cats = lower emissions, perfect for passing the sniffer. I dont know how they'll react to a visual but I'm sure they cant complain.

 

Sounds like a great way to pass