Cats?

[TurboD1987]

Can someone tell me what the difference is between a 2way and a 3way cat. converter? I see them both advertised and I need one now. Thanks
Dave

 

[UNGN]

It has to do with the molecules the converter catalysts (sp?)

3 way catalyst causes:
the oxidation of hydrocarbons by O2
the oxidation of CO by O2
the reduction of NO by CO.

I think a 2 way causes:
the oxidation of CO by O2
the reduction of NO by CO.
and doesn't do as good a job on the HC's

I'd get a three way for the test and test pipe for the other 364 days and 23 hours in a year.

 

[CanVan87GN]

If the Cat is permanent, Random Technologies free-flow Cat is a must. They work pretty good (still not as good as test pipe).

 

[TurboD1987]

Ok well I went and ordered a new cat. the walker universal 2 1/2 in and out and 13 1/4 and it is a 3 way part # 15033. All I ask of it is that it works for 1 day every 2 years. LOL
Dave

 

[salvageV6]

It should do that ok.

I thought 2 way was no air and 3 way included the air pump thingy. I dunno...

I may take my Random Tech. brand new cat. to the track for testing. Shouldn't be too hard to change out there.

Would be interesting to see if any boost is lost with it.

 

[gofstbuick]

A two way cat is a oxidation cat only. It combines O2 with HC and CO to make CO2 (carbon dioxide) and H2O (water), the byproducts of perfect combustion. A three-way-cat (TWC) has an additional bed that removes oxygen direvitives (sp) from NOx to created N2.
Salvage6:
the TWC used to need air to cool the mixture, but with the introduction of computer controls and O2 sensors, that became obsolete. Now most air injection systems are used to get the cat to light off when the engine is cold. The O2 sensor tries to maintain 14.7:1 a/f ratio. The best it can do is 14.5:1(rich) to 14.9:1 (lean). When it's rich in the cat, the cat uses this oportunity to reduce NOx (by putting combustion out), extra O2 is stored and when the mixture in the cat is lean, the store O2 and extra O2 from lean mixture is released to convert Hc and CO to CO2 and H2O. That's the short explanation, imagine a long version coming from a motor mouth like me .

 

[TurboD1987]

Originally posted by salvageV6
It should do that ok.

I thought 2 way was no air and 3 way included the air pump thingy. I dunno...

Yes the 3 way does have the air pipe on it but is capped from the factory.
Dave