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Old 08-14-2022, 03:08 PM   #1 (permalink)
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Catalytic converter do they work?



This video shows a car exhaust at high revs getting to 210c on the outside. So inside let's say 250-280c. If cats start operating at 400c and get more efficient at higher temps then they must not really work. A hybrid also only starts and stops,. 350c at the header but may never reach 400c at the cat??

Incidentally in the UK hybrid they do not get tested at mot..

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Old 08-14-2022, 03:45 PM   #2 (permalink)
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Old 08-14-2022, 11:16 PM   #3 (permalink)
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  1. The car was stationary. Exhaust temps don't heat up that much from idling, or even revving the engine in a stationary vehicle. If you want heat, put a load on the engine.
  2. The temperature of the exhaust tubing is going to be somewhat the average between the exhaust temp and ambient temp. I doubt the exhaust is only 280C or so. It is very likely much, much higher.
  3. The O2 sensor was the hottest part of the exhaust. It is also the closest object to the catalytic converter. Therefore, the catalytic converter is also the hottest part of the exhaust. I can only be the hottest part of the exhaust if it's working.
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Old 08-15-2022, 10:47 AM   #4 (permalink)
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Still does not answer. Exhaust gas temp has to be approximately 800c for substantial efficiency.

The other video was stationary also with no temps. Maybe at high load it's a little hotter on a highway but at all other times in traffic or urban areas it doesn't operate at all??

Besides once moving engine compartment air flow is designed to remove heat from that area

Not to worry
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Old 08-15-2022, 10:53 AM   #5 (permalink)
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Quote:
Originally Posted by Nathan jones View Post
Still does not answer. Exhaust gas temp has to be approximately 800c for substantial efficiency.

The other video was stationary also with no temps. Maybe at high load it's a little hotter on a highway but at all other times in traffic or urban areas it doesn't operate at all??

Besides once moving engine compartment air flow is designed to remove heat from that area
How do you know what the exhaust gas temperature is without measuring the exhaust gas temperature directly?

Where did you read that exhaust gas temperature has to be 800C for substantial efficiency? I heard it should be much less, closer to 300C. At 800C it sounds close to overheating and ruining the catalytic converter.

Again, catalytic converters do work. This isn't a conspiracy to use up precious metals that are hard to get.
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Old 08-15-2022, 11:33 AM   #6 (permalink)
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My mistake everybody, getting my f and c mixed up. They run from 4-600c. (752f) and damage from 900c. Still doubt mine goes that high and is on battery half of the time
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Old 08-15-2022, 11:42 AM   #7 (permalink)
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Sorry to waste everyone's time, it was more of an idle query I'm not too concerned
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Old 08-15-2022, 07:21 PM   #8 (permalink)
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No worries!

A simple test is to take the catalyst off. Trust me when I say you can smell the difference right away, even with an idling vehicle.
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Old 08-18-2022, 03:07 AM   #9 (permalink)
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Quote:
Originally Posted by Ecky View Post
A simple test is to take the catalyst off. Trust me when I say you can smell the difference right away, even with an idling vehicle.
For me it's easier to notice on carburettor-fed vehicles.

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