5 ms·

I personally don't really agree with regression in this area but more than one automotive engineer has told me that things have gotten to where the exhaust must

by kw71 9y ago

I personally don't really agree with regression in this area but more than one automotive engineer has told me that things have gotten to where the exhaust must be cleaner than the air taken in by the engine.

smileysteve 9y ago
This hyperbole doesn't really withstand the thought process; There is little reason that the exhaust shouldn't be cleaner than the air it is taking in. 1. There is an air filter that immediately takes out large particles (dust, dirt, mites, etc) 2. Emissions systems use hot wires to detect airflow precisely 3. O2 sensors readily adjusting fuel on the fly to ensure a complete burn. 4. A catalytic process using space metals that further ensures a clean burn Effectively, whether it's dusty, a cow has farted around you, or a chicken farm is producing ammonia; the modern ICE has the ability to detect this scenario and adjust faster that 8k times a second.
- headmelted 9y ago
  I know you have some solid points here, but all I can think about now is that we live in a world where a sensor exists that can detect cow farts at a rate of 8k per second.
- maxxxxx 9y ago
  "here is little reason that the exhaust shouldn't be cleaner than the air it is taking in." And it isn't anyway. Just stand next to a running engine in a badly ventilated area for a while and you'll know that engine doesn't make things better.
  - kw71 9y ago
    Actually, if you run a modern engine in a closed garage now, your eyes won't burn, you won't choke and it won't kill you. While this is a stupid thing to do, the bad stuff is only coming out before it's warmed up (meaning closed loop and catalyst warm enough to function) and if you back your car into the garage you can tell the difference the first time you do a cold start.
  - smileysteve 9y ago
    Better and Cleaner are 2 different things; No matter what, an ICE is going to output CO2 and H20; and depending on the fuel a few extra Cs. CO2 or H2O concentrations are enough to make things worse for an engine or a human, but are not necessarily dirty. NOX and CHs however are not as "naturally" in the air and producing them definitely makes the air "dirtier"
- kw71 9y ago
  This frustration arises from the situation that there are places where there is already more poison in the air than what comes out of the tailpipe of a modern, warmed up petrol vehicle. Los Angeles and Beijing are two examples where I have personally seen this situation on bad days. We are at the point now where mixture control and exhaust treatment leave nothing but carbon dioxide and water being emitted from a properly running automobile. With regard to parent's assertions: 1. The intake air cleaner is to keep particles out that will damage the engine (and eventually lead to lower performance and emissions control malfunction); 2. Whatever airflow meter, or not, on an engine is for combustion control, but its performance affects emissions output; 3. Exhaust o2 sensors, for 10-25 years depending on make and model, have already been telling the control system the results of combustion on each cylinder, for every combustion; 4. The catalysts are not magic. They are meant to react with specific products of combustion; There is nothing in an automobile, nor should there be, to detect and react with things like methane and ammonia. The only time you see a dust/smog detection is in luxury models that adjust the cabin ventilation in the presence of this for comfort of the occupants. There are no adjustments happening at a rate of 8 kHz: combustion in a cylinder is not even happening at this rate.
  - smileysteve 9y ago
    I pointed out methane because the modern sensor pack can and will detect fuels or inert gases in the air and reduce/add the amount of fuel added added to approach stoich. Then the combustion and catalytic process will break apart that ammonia and encourage its nitrogen to linger on its own as the hydrogens burn up or find some oxygens.
Angostura 9y ago
Presumably these engineers run a hose from the tail-pipe of their running car into their children’s bedrooms. Thought not.
RobLach 9y ago
Automotive engineers are telling you that internal combustion engines have been regulated to the point of being air purifiers? Are they working on hydrogen based engines?
- petre 9y ago
  Toyota is but sales have been underwhelming, infrastructure is lacking, the vehicle is quite ugly and you essentialy have a bomb (high pressure container) in your car - with the added disadvantage that hydrogen is odourless and the flames are invisible in daylight. https://en.wikipedia.org/wiki/Toyota_Mirai https://en.wikipedia.org/wiki/Toyota_Mirai
  - opencl 9y ago
    The Mirai isn't using a hydrogen engine, it's using fuel cells. There are also internal combustion engines that burn liquid hydrogen. Somewhat more practically it's fairly straightforward to convert existing gasoline engines to run off propane or compressed natural gas, you can get cars like this today but the refueling situation is of course not great.
    - petre 9y ago
      It runs on H2. You can achieve better torque/speed/traction control with electric motors and the drivetrain is also simpler. ICEs are better off converted to LPG or DME. CNG takes too much space and also uses higher pressure containers, while it can be easily converted to DME and stored in containers pressurized at 0.5 MPa.

by kw71 9y ago

smileysteve 9y ago

This hyperbole doesn't really withstand the thought process; There is little reason that the exhaust shouldn't be cleaner than the air it is taking in. 1. There is an air filter that immediately takes out large particles (dust, dirt, mites, etc) 2. Emissions systems use hot wires to detect airflow precisely 3. O2 sensors readily adjusting fuel on the fly to ensure a complete burn. 4. A catalytic process using space metals that further ensures a clean burn Effectively, whether it's dusty, a cow has farted around you, or a chicken farm is producing ammonia; the modern ICE has the ability to detect this scenario and adjust faster that 8k times a second.

headmelted 9y ago
I know you have some solid points here, but all I can think about now is that we live in a world where a sensor exists that can detect cow farts at a rate of 8k per second.
maxxxxx 9y ago
"here is little reason that the exhaust shouldn't be cleaner than the air it is taking in." And it isn't anyway. Just stand next to a running engine in a badly ventilated area for a while and you'll know that engine doesn't make things better.
- kw71 9y ago
  Actually, if you run a modern engine in a closed garage now, your eyes won't burn, you won't choke and it won't kill you. While this is a stupid thing to do, the bad stuff is only coming out before it's warmed up (meaning closed loop and catalyst warm enough to function) and if you back your car into the garage you can tell the difference the first time you do a cold start.
- smileysteve 9y ago
  Better and Cleaner are 2 different things; No matter what, an ICE is going to output CO2 and H20; and depending on the fuel a few extra Cs. CO2 or H2O concentrations are enough to make things worse for an engine or a human, but are not necessarily dirty. NOX and CHs however are not as "naturally" in the air and producing them definitely makes the air "dirtier"
kw71 9y ago
This frustration arises from the situation that there are places where there is already more poison in the air than what comes out of the tailpipe of a modern, warmed up petrol vehicle. Los Angeles and Beijing are two examples where I have personally seen this situation on bad days. We are at the point now where mixture control and exhaust treatment leave nothing but carbon dioxide and water being emitted from a properly running automobile. With regard to parent's assertions: 1. The intake air cleaner is to keep particles out that will damage the engine (and eventually lead to lower performance and emissions control malfunction); 2. Whatever airflow meter, or not, on an engine is for combustion control, but its performance affects emissions output; 3. Exhaust o2 sensors, for 10-25 years depending on make and model, have already been telling the control system the results of combustion on each cylinder, for every combustion; 4. The catalysts are not magic. They are meant to react with specific products of combustion; There is nothing in an automobile, nor should there be, to detect and react with things like methane and ammonia. The only time you see a dust/smog detection is in luxury models that adjust the cabin ventilation in the presence of this for comfort of the occupants. There are no adjustments happening at a rate of 8 kHz: combustion in a cylinder is not even happening at this rate.
- smileysteve 9y ago
  I pointed out methane because the modern sensor pack can and will detect fuels or inert gases in the air and reduce/add the amount of fuel added added to approach stoich. Then the combustion and catalytic process will break apart that ammonia and encourage its nitrogen to linger on its own as the hydrogens burn up or find some oxygens.

Angostura 9y ago

Presumably these engineers run a hose from the tail-pipe of their running car into their children’s bedrooms. Thought not.

RobLach 9y ago

Automotive engineers are telling you that internal combustion engines have been regulated to the point of being air purifiers? Are they working on hydrogen based engines?

petre 9y ago
Toyota is but sales have been underwhelming, infrastructure is lacking, the vehicle is quite ugly and you essentialy have a bomb (high pressure container) in your car - with the added disadvantage that hydrogen is odourless and the flames are invisible in daylight. https://en.wikipedia.org/wiki/Toyota_Mirai https://en.wikipedia.org/wiki/Toyota_Mirai
- opencl 9y ago
  The Mirai isn't using a hydrogen engine, it's using fuel cells. There are also internal combustion engines that burn liquid hydrogen. Somewhat more practically it's fairly straightforward to convert existing gasoline engines to run off propane or compressed natural gas, you can get cars like this today but the refueling situation is of course not great.
  - petre 9y ago
    It runs on H2. You can achieve better torque/speed/traction control with electric motors and the drivetrain is also simpler. ICEs are better off converted to LPG or DME. CNG takes too much space and also uses higher pressure containers, while it can be easily converted to DME and stored in containers pressurized at 0.5 MPa.