Running without airpump damage stock cat converter?
05-09-08, 06:13 PM
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Running without airpump damage stock cat converter?
If i take out the airpump will this kill my cat converter ?
If so how long do I have before I should replace the cat before it starts posing a problem from being damange from running without an airpump
If so how long do I have before I should replace the cat before it starts posing a problem from being damange from running without an airpump
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05-09-08, 08:44 PM
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The real question is why would you want to run without an airpump?Since the magnetic clutch dis-engages at 3000rpm,it does not cost you anything at high rpm.Below 3000rpm it keeps your exhaust clean.
I see not point unless you are building a race car and need to lose the weight.
I see not point unless you are building a race car and need to lose the weight.
05-09-08, 10:51 PM
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The real question is why would you want to run without an airpump?Since the magnetic clutch dis-engages at 3000rpm,it does not cost you anything at high rpm.Below 3000rpm it keeps your exhaust clean.
I see not point unless you are building a race car and need to lose the weight.
I see not point unless you are building a race car and need to lose the weight.
I will probobly end up leaving it on because i dont wanna play the guessing game with emitions stuff.
Just 1 quick question then.
When i wish to upgrade the intercooler piping .. How can i get that skinny pipe that bends over the airpump nice and wide with more diameter? =)
I am planning on going single turbo, and I think it would just be dumb to keep the airpump in there doing so.
Now since emitions have really come down to either legal car or not legal car... how do people get by with single turbo FD's ?
05-10-08, 03:37 AM
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Running without an air pump will most certainly damage the main catalytic converter. The pump is an integral part of the catalytic converter system. The idea behind the cat is that once the material is warmed up sufficiently, unburned hydrocarbons (oil and gasoline) that has not been fully combusted in the engine will pass through the cat. Platinum and other catalysts in the catalytic converter will allow the unburned hydrocarbons to be safely "burned" without a flame or explosion, reducing hydrocarbon emissions. For this to happen, you will need the presence of oxygen, hence the air pump. Without the addition of fresh oxygen through the air pump, the catalytic converter will eventually overheat scavenging the remaining oxygen from the exhaust stream (this "burning" also generates heat and the air also acts to aid in cooling the cat) and the refractory material will deteriorate, crack, melt, and eventually fail.
YES it may take some time, even a few years, but it will prematurely and eventually fail.
Remember, the air pump only runs up to about 3500rpm's so if you think it is robbing lots of power, it is not.
A cat almost never fails on it's own. Except for wear, the cat will work indefinitely if conditions are right. Failure of a cat is only a symptom of some other component failing like an O2 sensor, failed air pump, refractory damage or deterioration inside the cat, high exhaust temp, oil consumption, leaking injector, rich mixture, etc.
If you choose to remove the pump, remove the cat and put a pipe in. This way, you won't have to buy another one.
Tim
PS Yes, there are catalytic converters that work without an air pump. They are also designed with different criteria for the exhaust stream gasses that pass through the cat. Case in point, the pre-catalytic converter. It works without the addition of an air pump, but it's function is different than the main catalytic converter.
Also remember, the inherent design of a rotary engine (except the Renesis) creates a condition where unburned fuel is wiped out of the combustion chamber to the exhaust by the apex seal and the periperal exhaust ports. This creates an extremely high output of hydrocarbons. Why do you think that the early year RX7's had three catalytic converters in line? This is why the Renesis engine was developed and it reduced hydrocarbon output by 50% and increased fuel economy. The unburned fuel that was initially just wiped out the periperal exhaust port is now being reintroduced in the intake charge again each time.
YES it may take some time, even a few years, but it will prematurely and eventually fail.
Remember, the air pump only runs up to about 3500rpm's so if you think it is robbing lots of power, it is not.
A cat almost never fails on it's own. Except for wear, the cat will work indefinitely if conditions are right. Failure of a cat is only a symptom of some other component failing like an O2 sensor, failed air pump, refractory damage or deterioration inside the cat, high exhaust temp, oil consumption, leaking injector, rich mixture, etc.
If you choose to remove the pump, remove the cat and put a pipe in. This way, you won't have to buy another one.
Tim
PS Yes, there are catalytic converters that work without an air pump. They are also designed with different criteria for the exhaust stream gasses that pass through the cat. Case in point, the pre-catalytic converter. It works without the addition of an air pump, but it's function is different than the main catalytic converter.
Also remember, the inherent design of a rotary engine (except the Renesis) creates a condition where unburned fuel is wiped out of the combustion chamber to the exhaust by the apex seal and the periperal exhaust ports. This creates an extremely high output of hydrocarbons. Why do you think that the early year RX7's had three catalytic converters in line? This is why the Renesis engine was developed and it reduced hydrocarbon output by 50% and increased fuel economy. The unburned fuel that was initially just wiped out the periperal exhaust port is now being reintroduced in the intake charge again each time.
Last edited by Tim McCreary; 05-10-08 at 03:55 AM. Reason: Some more information
05-11-08, 11:59 PM
#12
Renesis increased fuel economy? Lol
And I have never seen evidence that removing an air pump shortens the life of a catalytic converter. It reduces the effectiveness but thats about it. As such, it makes no sense to remove the air pump if you arent going to put in a mid-pipe.
And I have never seen evidence that removing an air pump shortens the life of a catalytic converter. It reduces the effectiveness but thats about it. As such, it makes no sense to remove the air pump if you arent going to put in a mid-pipe.
05-12-08, 06:50 AM
#13
I will have to disagree that there isnt any performance upgrades by removing it. If you are running below 3500rpm, in say an autocross situation, i think you will notice it. I found a very noticeable increase in low end grunt by disconnecting mine.
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/disconnect-airpump-%3D-car-faster-755385/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/disconnect-airpump-%3D-car-faster-755385/
05-12-08, 08:14 AM
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05-12-08, 09:47 PM
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Running without an air pump will most certainly damage the main catalytic converter. The pump is an integral part of the catalytic converter system. The idea behind the cat is that once the material is warmed up sufficiently, unburned hydrocarbons (oil and gasoline) that has not been fully combusted in the engine will pass through the cat. Platinum and other catalysts in the catalytic converter will allow the unburned hydrocarbons to be safely "burned" without a flame or explosion, reducing hydrocarbon emissions. For this to happen, you will need the presence of oxygen, hence the air pump. Without the addition of fresh oxygen through the air pump, the catalytic converter will eventually overheat scavenging the remaining oxygen from the exhaust stream (this "burning" also generates heat and the air also acts to aid in cooling the cat) and the refractory material will deteriorate, crack, melt, and eventually fail.
YES it may take some time, even a few years, but it will prematurely and eventually fail.
Remember, the air pump only runs up to about 3500rpm's so if you think it is robbing lots of power, it is not.
A cat almost never fails on it's own. Except for wear, the cat will work indefinitely if conditions are right. Failure of a cat is only a symptom of some other component failing like an O2 sensor, failed air pump, refractory damage or deterioration inside the cat, high exhaust temp, oil consumption, leaking injector, rich mixture, etc.
If you choose to remove the pump, remove the cat and put a pipe in. This way, you won't have to buy another one.
Tim
PS Yes, there are catalytic converters that work without an air pump. They are also designed with different criteria for the exhaust stream gasses that pass through the cat. Case in point, the pre-catalytic converter. It works without the addition of an air pump, but it's function is different than the main catalytic converter.
Also remember, the inherent design of a rotary engine (except the Renesis) creates a condition where unburned fuel is wiped out of the combustion chamber to the exhaust by the apex seal and the periperal exhaust ports. This creates an extremely high output of hydrocarbons. Why do you think that the early year RX7's had three catalytic converters in line? This is why the Renesis engine was developed and it reduced hydrocarbon output by 50% and increased fuel economy. The unburned fuel that was initially just wiped out the periperal exhaust port is now being reintroduced in the intake charge again each time.
YES it may take some time, even a few years, but it will prematurely and eventually fail.
Remember, the air pump only runs up to about 3500rpm's so if you think it is robbing lots of power, it is not.
A cat almost never fails on it's own. Except for wear, the cat will work indefinitely if conditions are right. Failure of a cat is only a symptom of some other component failing like an O2 sensor, failed air pump, refractory damage or deterioration inside the cat, high exhaust temp, oil consumption, leaking injector, rich mixture, etc.
If you choose to remove the pump, remove the cat and put a pipe in. This way, you won't have to buy another one.
Tim
PS Yes, there are catalytic converters that work without an air pump. They are also designed with different criteria for the exhaust stream gasses that pass through the cat. Case in point, the pre-catalytic converter. It works without the addition of an air pump, but it's function is different than the main catalytic converter.
Also remember, the inherent design of a rotary engine (except the Renesis) creates a condition where unburned fuel is wiped out of the combustion chamber to the exhaust by the apex seal and the periperal exhaust ports. This creates an extremely high output of hydrocarbons. Why do you think that the early year RX7's had three catalytic converters in line? This is why the Renesis engine was developed and it reduced hydrocarbon output by 50% and increased fuel economy. The unburned fuel that was initially just wiped out the periperal exhaust port is now being reintroduced in the intake charge again each time.
Will I be able to pass emitions with an aftermarket High Flow Cat?
05-13-08, 07:49 AM
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Only if you have a functioning air pump and a good converter.There is zero chance of passing the Ontario emissions test without the air pump.
Just as an aside,if you do not like the standard air pump location,you could consider getting an RX-8 electric air pump which you could locate where it suites you.Also the electric air pump could be controlled using the existing wiring and PCM.
Just as an aside,if you do not like the standard air pump location,you could consider getting an RX-8 electric air pump which you could locate where it suites you.Also the electric air pump could be controlled using the existing wiring and PCM.
05-13-08, 10:00 AM
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Have you done this? Sounds very interesting. I'm not an innovator and way too stupid to figure things out on my own but occasionally, I can follow what other folks have done....
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