Only one catalytic converter? opinions??

[cbass]

Hey guys, I was over at GBR the other day talking to Bill and picking up some stuff. We got to chatting about exhausts because I am going the custom route during this rebuild I am doing on the d-90. I had planned on making the new system very similar to the stock one with the exception of headers and slightly bigger pipe, the general layout would be almost the same though.

Anyway, he said that on one of his Range Rovers he took out the catalytic converters and put straight pipe in place of them. Then he put one single catalytic converter right in front of the muffler but after the y-pipe comes together. He claims he still passed emissions and everything with it. Now, my question is, have any of you seen this before and what are your thoughts/opinions?

As a side note, I have thought it through and like the idea... the O2 sensors shouldn't be a problem because it will be going on a 1994 d-90 which only has one sensor per side and they are both pre-cat anyway. What do you guys think??

 

[rufus]

There are two things to think about here.

There are some laws that require the catalytic converter to be in its original location. This does not mean it can not be altered (upgraded only after failure of the original unit). But...I don't know your local laws.

Second, the closer to the engine the better when placing a converter in a system. Look at any late model vehicle and see how close they are to the header/manifold. There is a point where you can be too close, however. The converter "works" when it's "lit" or brought to temperature, therefor, the closer the better. It lights off faster when closer to the header/manifold. There is a point where they can get too far away and this can adversely effect your tune, i.e. causing a rich condition for too long after start up, eventually fouling things up. The OBDI system is more forgiving of this however and can easily be tuned/ adjusted accordingly.

They make some very small, very low profile cat's for not too much money these days that can do a better job than a stock unit and do not supply ANY back pressure. These things can pass the sniffer even in 400 + hp conditions. I have installed some that you could not only see a light bulb through, you could read the letters on the top of the light bulb. Now that is free flow.

With all that said, it will work, but it may be too far away, especially on a cold morning start.

 

[roverX]

To add to that, your vehicle must pass a visual inspection in some states. Check on your state.

 

[p m]

it should work just fine.
however...
you won't be able to register it in California, and, if I understand the emission laws correctly, it is illegal to do in the U.S. (but not checked visually in many places).

 

[rrefx]

I use to work for a shop here in Utah that built custom cars. Cats was one of our biggest headaches, mainly because people would want to put true duel exhaust, and we had to do it after the cat if it only had one, because it is illeagle to add a second. Utah Law pretty much states that emissions wise, if it came with it, you have to keep it. A lot of towns choose not to act on that however, but that won't stop the highway patrole from ticketing you on it if they catch you, which teh chances are slim. Also not many shops are going to check that the number of cats you have is right, just as long as you have a cat, they are happy. Bill probably gets away with it because wherever he takes them just doesn't check, but that doesn't mean that thats what teh law is. The truth is, you can probably get away with it, without ever having it be a problem. It's just that one time someone doesw check that will get you. Whatever you decide to do, good luck with it.

Ryan

 

[marc olivares]

Brad,

i know a shop by your old mans house that will "help" you through this.
and not much of an issue in Utah as long as you have a cat.
call me tomorrow
we need to chat anyway

 

[cbass]

shoot, I wish I would have read your post today Marc, I just got off the phone with you a few hours ago, but didn't even think to talk about exhausts because I hadn't read this yet. Anyway, I'll chat with you about it on Thursday when we get together, I'm interested in your take on it.

Interesting info about heating up the cats, I hadn't thought of that and that would definately be a reason to just put them in their stock location. Oh well, I have a while before I have to worry about the exhaust.

Thanks guys! If anybody else has advice, suggestions, I'm interested!

PS, RUFUS, what are the makes and models of some of the cats you are referring to?

 

[rufus]

Random Tech: www.thunderracing.com/catalog/?action=categories&pcid=8

or Magnaflow (made by Car Sound) http://www.car-sound.com/

I have had good results with both of these.

Or you could accidentally hollow out the cat alltogether and forget about where you put it or if it will restrict flow. But I would never suggest such a thing (cough) nor have I ever sucessfully done it (cough cough). It sounds like you only have to pass a visual test, so worrying about placement is just that, a placement issue. With no sniffer test, you do not have to worry about it "doing its job".

Hope this helps.