Running a Cat w/o Airpump
10-12-10, 01:39 PM
#1
Running a Cat w/o Airpump
Research says it'll just melt the cat right out. It's pointless. Etc. Etc. That's why in both of my FC's I had the airpump taken out and removed the cat.
Now I'd really like to get rid of the terrible smell but I don't want to put an airpump back in. Any suggestions on what I should do? I won't be doing any racing and it'll be mostly street driving.
I don't want any theoretical answers because I know it theoretically would fail. But has anyone actually done this and gotten success or know of any other way?
Now I'd really like to get rid of the terrible smell but I don't want to put an airpump back in. Any suggestions on what I should do? I won't be doing any racing and it'll be mostly street driving.
I don't want any theoretical answers because I know it theoretically would fail. But has anyone actually done this and gotten success or know of any other way?
10-12-10, 03:11 PM
#2
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the reason you NEED an air pump is very simple.
the converter MUST run at a mixture of around 14.7:1 air/fuel.
due to the physical layout of the rotary engine it cannot run without misfires at low speeds that lean. so the engine is tuned to run without misfiring, and then the air pump air is added in to make the mixture compatible with the cat.
note this is for sub 1500rpm running, in the 1500+ rpm range, the engine CAN run 14.7:1 without the airpump, and in fact depending on throttle position, it will vent the air pump air to the outside.
so in summary, at low engine speeds, and small throttle positions, the cat won't like you.
the converter MUST run at a mixture of around 14.7:1 air/fuel.
due to the physical layout of the rotary engine it cannot run without misfires at low speeds that lean. so the engine is tuned to run without misfiring, and then the air pump air is added in to make the mixture compatible with the cat.
note this is for sub 1500rpm running, in the 1500+ rpm range, the engine CAN run 14.7:1 without the airpump, and in fact depending on throttle position, it will vent the air pump air to the outside.
so in summary, at low engine speeds, and small throttle positions, the cat won't like you.
10-12-10, 04:09 PM
#3
From reading this post http://www.turborx7.com/Cat.htm , it seems that there are cats out there that can run without air injection. I care less about actual emissions results than the smell.
10-12-10, 05:51 PM
#4
I ran a catco cat from a local muffler shop on my 88 GTU, without an airpump. I had it in there for maybe 15k miles before I removed it. It was in ok shape and did not look obviously clogged. If you are just looking to clean up the smell then you should be ok for a while without an airpump. It's not going to die in a month or two if that's what you're worried about. You won't pass a tailpipe test without the airpump though.
10-13-10, 03:49 PM
#7
I contacted Vibrant racing that makes universal metal-core high-flow cats. He informs me that cat does not need any form of air injection but I don't know if he knew about the point that j9fd3s was making.
The cat would only be there for the purpose of taking out the smell, I don't care about emissions.
A question that the Vibrant rep asked me was what temperature I would expect the exhaust gasses would be. I know the rotary engine runs very hot but there are random numbers flying around. What kind of temperatures would I expect from city/highway driving?
The cat would only be there for the purpose of taking out the smell, I don't care about emissions.
A question that the Vibrant rep asked me was what temperature I would expect the exhaust gasses would be. I know the rotary engine runs very hot but there are random numbers flying around. What kind of temperatures would I expect from city/highway driving?
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10-13-10, 04:02 PM
#8
I havent read everyones post but regarding the OP I have removed all emissions except for cat and I dont have a heavy gas smell and I passed emssions. However my cat is new <1yr old. so replacing your cat may help.
Also my cat is fairly large and not high flow.
Also my cat is fairly large and not high flow.
10-13-10, 04:52 PM
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I contacted Vibrant racing that makes universal metal-core high-flow cats. He informs me that cat does not need any form of air injection but I don't know if he knew about the point that j9fd3s was making.
The cat would only be there for the purpose of taking out the smell, I don't care about emissions.
A question that the Vibrant rep asked me was what temperature I would expect the exhaust gasses would be. I know the rotary engine runs very hot but there are random numbers flying around. What kind of temperatures would I expect from city/highway driving?
The cat would only be there for the purpose of taking out the smell, I don't care about emissions.
A question that the Vibrant rep asked me was what temperature I would expect the exhaust gasses would be. I know the rotary engine runs very hot but there are random numbers flying around. What kind of temperatures would I expect from city/highway driving?
my WAG would be something in the 1650-1750F range, at peak.
ive actually never seen numbers for a cat, if you find out post em up!
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