hollow cat question

[paintball4fun21]

i have the stock 2g exhaust on my talon and i was wondering about hollowing out the cat. Im getting catback exhaust in a few months but wanted to hollow it out for a few extra hp. im not worried about emissions but i was wondering about the other pros and cons.
thanks!!

 

[nightspeed87]

^ that's true. I'll cede to some truth about a bunch of people doing it, however, just because it can be done, doesn't mean everybody is going to go out and do it, obviously. But most people with a 3-in. exhaust don't have an option for a cat anyway.

Oh, and what is this smell everybody is complaining about. I run a full 3" exh. and I have to drive with the windows down (no A/C...) and I don't have that issue...unless I'm backing up. If yall are driving with the windows up and having issues of smelling like gas/exhaust, perhaps you have another issue. Like huge holes in the back of the car.

Anyway, I believe the answer to the original post has been found. It's a matter of priorities. Everybody's are different. Whether they be a polluting, power-mad, carnivorous, A-hole damn Texan, or a tree-huggin', veggie-eaten, yankee (or Californian) It's personal preference.

If we are going to have a "how we can stop pollution" thread (which perhaps we should) it should be done in the hangout. Happy DSMing everybody! (damn polluting, gas-wasting DSMs....)

Not to sound like a hyprocrit but I once did have my cat hollowed out and yea I could smell the carbon monoxide really strong when I stopped at a light and the wind carried a gust of it.. But if the windows are up you shouldnt smell it unless theres an exhaust leak, or a opening in your car that shouldnt be.... And yea everyone has their own preference, but normally when one person tried to get away with something, and the other person says oh you can do this too, then they end up doing it... If you run with no cat then fine, just dont advertise it to bring other ppl along keep it to yourself.... Thats all im saying...

( On contrary I wouldnt mind doing it if my car wasnt everyday driver and I only seen the track in it.... )

 

[420Adriver]

I've never ran with a cat I just like making good points.

 

[xveganxcowboyx]

Not to sound like a hyprocrit but I once did have my cat hollowed out and yea I could smell the carbon monoxide really strong when I stopped at a light and the wind carried a gust of it..

Carbon monoxide is odorless.

 

[nightspeed87]

Carbon monoxide is odorless.

well exhaust gas... You know what im talking about.

 

[xveganxcowboyx]

I'm not positive, but I believe it's probably the NOx that smells. Sulfur emissions can cause smells, but that's more the mark of old diesel fuel. Unfortunately smell alone can't tell you how 'clean' your engine is running. I ran without an exhaust for a while and it smelled fine. That doesn't mean I wasn't putting out mass amounts of pollutants.

 

[jumpfroggy]

From what I've seen/read, the simple "high flow cats" that look like pipes are just that; pipes. A catalytic converter is expensive because of the materials used to make them (platinum?), and they cause a chemical reaction that reduces emissions. A pipe, no matter what you call it, will not do this. So ebay "high flow cats" are usually just mislabelled test pipes. This is also why it's illegal to replace a catalytic converter, except under certain circumstances (I think it was >15 years old or non-functioning in RI, IIRC)... don't want all those heavy metals going in the landfill.

So test pipes (which look like resonators) are not really high flow cats at all, they're just test pipes. Real high flow cats reduce emissions but are better flowing.

http://www.roadraceengineering.com/parts/dp/rredp-2gfwd-options.jpg

RRE has a great pic... you see the race pipe/test pipe on the top, and the high-flow cat on the bottom. High flow should be about $100-200, test pipe will be <$100 (more like $50).

I'm curious about the real world difference between a high-flow and a test pipe. My thoughts; if you're budget, then upgrade the rest of the exhaust. If you've got money, go high-flow and full 3". I know you'll get a performance gain from gutting a cat, but it does seem irresponsible. It is a personal thing, and I can't bring myself to do it. People here drive without insurance to be cheap and because they don't mind putting other people at risk. I won't do it. Same thing with the test pipe, for a daily driven car I just won't do it. For a track car, would seem ok.

Another pro/con, which no one's mentioned yet, is that gutting or removing a cat will make the exhaust louder. I'm going for a quiet car, so this is a huge drawback to most aftermarket downpipes that eliminate the cat. I'd rather just throw a real high flow cat in there and save trees, quiet the exhaust, go fast, and feel good about myself. Anyone used both test pipes and high flows? Can anyone compare the sound and performance?

 

[AndrewD5418]

From what I've seen/read, the simple "high flow cats" that look like pipes are just that; pipes. A catalytic converter is expensive because of the materials used to make them (platinum?), and they cause a chemical reaction that reduces emissions. A pipe, no matter what you call it, will not do this. So ebay "high flow cats" are usually just mislabelled test pipes. This is also why it's illegal to replace a catalytic converter, except under certain circumstances (I think it was >15 years old or non-functioning in RI, IIRC)... don't want all those heavy metals going in the landfill.

So test pipes (which look like resonators) are not really high flow cats at all, they're just test pipes. Real high flow cats reduce emissions but are better flowing.

http://www.roadraceengineering.com/parts/dp/rredp-2gfwd-options.jpg

RRE has a great pic... you see the race pipe/test pipe on the top, and the high-flow cat on the bottom. High flow should be about $100-200, test pipe will be <$100 (more like $50).

I'm curious about the real world difference between a high-flow and a test pipe. My thoughts; if you're budget, then upgrade the rest of the exhaust. If you've got money, go high-flow and full 3". I know you'll get a performance gain from gutting a cat, but it does seem irresponsible. It is a personal thing, and I can't bring myself to do it. People here drive without insurance to be cheap and because they don't mind putting other people at risk. I won't do it. Same thing with the test pipe, for a daily driven car I just won't do it. For a track car, would seem ok.

Another pro/con, which no one's mentioned yet, is that gutting or removing a cat will make the exhaust louder. I'm going for a quiet car, so this is a huge drawback to most aftermarket downpipes that eliminate the cat. I'd rather just throw a real high flow cat in there and save trees, quiet the exhaust, go fast, and feel good about myself. Anyone used both test pipes and high flows? Can anyone compare the sound and performance?

Well, don't trees live off the stuff our cars put out, and convert it back into breathable air? We just need more trees . My friend has a high flow on, put a test on, and seen no difference in sound, not sure about performance though, and put the cat back on. I'd imagine you lose a little bit of power, not much though (Depending on your actual output). But don't the cats heat up the exhaust alot more?

 

[jumpfroggy]

I know they operate at high temp's to facilitate the chemical reaction (and get rid of the bad stuff so the trees can live and keep feeding us oxygen). Don't know if it heats the exhaust up more, or if it affects flow due to temp.

 

[toojung2die]

I know they operate at high temp's to facilitate the chemical reaction (and get rid of the bad stuff so the trees can live and keep feeding us oxygen). Don't know if it heats the exhaust up more, or if it affects flow due to temp.

The cat absorbs and retains heat from the exhaust gases. The oxidation of unburned hydrocarbon and carbon monoxide in the catalyst causes added heat. The internal temperature of a cat is about 1200 degrees. A well-made high flow cat will reduce emissions and create negligible restriction. The hp increases from running a test pipe instead of a cat are not enough to justify the additional pollutants released into the environment. Here is a good lesson on high flow cats:
http://www.randomtechnology.com/technical.html

 

[Blackmitzu]

I would get an electric cutout and install it before the cat. You can then open it on the fly for 25hp extra, then close it when you want to hear yourself think.