Myth or Fact?

[Griemster1]

Removing Catalytic convertor impoves gas mileage? Any input?

 

[Atrus]

Eh, I think it can depend on the application. Some cats flow better than others, and some engines are more sensitive to the right amount of backpressure than others.

 

[Griemster1]

Well on KJ's?

 

[Atrus]

Not trying to be a pain and dodge the question, but to truly know you'd have to do a dyno run, remove the cat right away, and then do another dyno run. Maybe someone on LOST has done this? Slim chance, but you never know.

 

[Dave]

Not trying to be a pain and dodge the question, but to truly know you'd have to do a dyno run, remove the cat right away, and then do another dyno run. Maybe someone on LOST has done this? Slim chance, but you never know.

I would agree with Kevin.

Besides, it is not legal and if you have emissions checks with your inspections in your state it wouldn't pass.

Just some thoughts.

Dave

 

[Atrus]

MI currently has no emissions checks.

In a previous vehicle I did put in a high-flow cat. Can't say how much it helped as I did other exhaust work at the same time, so not sure what my gains where really attributed to.

 

[kj924]

Also depends if the cat is partially plugged or not. A half plugged cat will drop your mileage.

To test the theroy, you need to dyno a new rig off the lot.

 

[AlexKJ]

Sorry buddy... There is no such thing as a hi-flow cat... No matter what they say...

Cheers!

 

[Atrus]

Sorry buddy... There is no such thing as a hi-flow cat... No matter what they say...

Cheers!

I won't say either way, but I find it hard to believe an aftermarket high-flow unit wouldn't flow better than an OEM. They can do it with mufflers, right?

The only experience I have in putting in a high-flow cat was when I removed an extremely restrictive bend, upgraded the pipe from 2.25" to 2.5", replaced the cat with the high-flow unit, and also removed the resonator. So, while I can't speak from experience that the high-flow cat did or didn't help, I lean towards saying that it did.

 

[AlexKJ]

Judge for yourself...

 

[Atrus]

These substrates are made like a beehive honeycomb and are comprised of 400 cells per square inch across their surface. In theory, an aftermarket cat is higher flow than it's O.E. counterpart because the O.E. converter has a substrate made up of 700 cells per square inch, so the exhaust flow with and aftermarket converter is a little freer, but not dramatic! We do carry a few universal converter numbers that have a 200 cell substrate but they are like I said, universal. They sometimes require extensive welding and cutting of the original exhaust system, so for many applications they are just not practical.

Can't comment on the cell count of what I used, but I did use a universal. Either way, I needed a new cat to go from 2.25" to 2.5". Interesting info.

 

[KJ zGal]

Removing the CC will also prevent you from passing inspection--at least in NY.

 

[sleeve]

Removing the catalyist on the KJ will cause the check engine lights to iluminate and cause the engine to try and correct itself because of the extra rich emissions. This would hurt performance more than anything.

Do not remove the catalyist [4 of them]

 

[Atrus]

Removing the catalyist on the KJ will cause the check engine lights to iluminate and cause the engine to try and correct itself because of the extra rich emissions. This would hurt performance more than anything.

Do not remove the catalyist [4 of them]

Are you sure on that? I don't think it'll affect performance, I think it's just to trigger a CEL.

If you want to kill the Check Engine light, you should be able to find a plugin O2 "spoof". Of course, this would be illegal and nobody should do it, but theoretically, it works

 

[Dave]

AlexKJ.....interesting info you posted about the so called "high flow cat". So there is no such thing in reality according to that website.

OP should send an e-mail to "Mythbusters".

Dave

 

[Prospect62]

Kinda of a foolish idea. Any gain you might see in MPG would be offset by the fact that the engine wouldn't run right, you'd get numerous OBD II codes and you'd be emitting more pollutants.

Get new plugs, an air filter and change the oil. If the gas mileage still isn't good enough for ya, you don't belong in a Jeep.