It seems today’s engine designs are super efficient in MPG, using less fuel for the same or greater power, than previous generations. And completely and cleanly burning the fuel too!
With that said, do catalytic converters serve an actual purpose in “cleaning” the exhaust before it is exhausted? Or is it a leftover relic from days of dirtier engines?
Yes, they are an important part of the pollution reduction systems on your car. Here's an explanation:
https://www.youtube.com/watch?v=lJiznlz5buc
It's the catalytic converters that permit today's engines to be as clean as they are. In fact since the advent of 3-way catalysts, pollutants have been reduced to the point where further cleanup is well into diminishing returns. Young people in the U.S. today have never really experienced air pollution like we had 50+ years ago.
70% reduction in vehicle pollution is significant. It used to look more like this ...
Yes, I have been in that kind of stuff, it was common in major cities. Los Angeles was usually the worst due to its being in a basin surrounded by mountains. Pollutants would be trapped and just hang around.
Engines are FAR from perfect. The best gasoline internal combustion engine is still only about 20% efficient. (20% of the energy released from fuel is used to propel the vehicle forward.) This has not changed a great deal over time.
About 1% of the fuel will pass through the engine as unburned hydrocarbons. In the neighborhood of 1.5 ounces per hour or 17 cubic feet of vapor.
The engine also produces similar proportions of sulphur dioxide, and monoxides (CO & NO) which are nasty, reactive substances (free radicals) that are toxic to humans. The catalytic converter significantly reduces the amount of these that comes out, by turning them into more inert molecules like CO2 and NO2.
Can you imagine the air quality in busy places like Los Angeles if cars didn't have CC's? It would look like Beijing China. People with respiratory illness would not be having a good time.
These by-products are unavoidable. Combustion is an imperfect, dirty process, and gasoline is cocktail of many different impure petroleum distillates, not a pure substance like hydrogen. These engines will never really be "clean".
Your use of superlatives like "super efficient" and "completely and cleanly burning " sound a lot like the jingo advertised by the manufacturers to sell more cars.
Not sure if this question is serious....
Yes, they serve an actual purpose. They burn out many of the harmful pollutants in the exhaust before spewing them into the air.
Ever hear of smog? This combats that issue.
For those saying the younger guys are lucky not to have to sit in gas fumes while they drive (I agree 100% with that BTW), these guys constantly come into the shop having hacked off their converters for "more power", "more noise", etc. and they are sitting in fumes, many in brand new cars, talking about how great it is and how it "smells like a race car." Nah man...smells like cancer. Ever read the stickers on a gas pump warning about long term exposure to gas vapors causing cancer? That's exactly what you are exposing yourself to by deleting the converters which, by the way, is a FEDERAL crime. Many shops won't delete them, mine included.
Quick fact: deleting your cats does not add power. In fact, it can cause all kinds of issues which is why I see so many of these modern cars come in. "I don't know why I have a CEL". First question we ask: "Did you delete the cats?" The VAST majority answer yes, and then it gets into the cost to fix the mistake of removing them.
TL;DR: YES, they have a very important purpose and you should have them on the car. For higher performance applications, "green cats" are available which flow at a higher rate but still burn off C.A.R.B. - approved levels of pollutants. Kooks makes very good ones, as an example. Very expensive, but worth it.
Not that I recommend deleting cats, but I was under the understanding that deleting cats aka straight piping gets you more horsepower? Isn’t that the alleged primary reason for doing it?
It’s a serious question. I hear about a bunch of stuff that I find questionable, so I seek out the truth from places I trust.
Straight piping does not add power. That has been proven a myth for some time now. You actually lose back pressure, which causes torque to go down as well. As you said, it is commonly talked about as a way to add power. However, on modern cars, it simply is not the case.
In older cars, would straight piping add 🐴 power?
Only if paired with other mods like long tube headers or forced induction. The thing is that modern cars are computer controlled so messing with the parameters messes with performance. On older cars, there weren't many restrictions anyway so straight piping doesn't add much as the exhaust is essentially free flowing already.
Some cars have multiple catalytic converters. Probably to meet emmision standards.
That is exactly why
catalytic converters need 3 stages. Some separate stages into separate cans, and some don't. It's in the video.
Isn't it then possible in this day and age that a way to make engines pollute less without such an expensive device?
I just can't believe that a a well running and tuned engine needs all the emission controls that are now being used.
It just seems to me that engines are being strangled by these "improvements"
Guess it's time to reserve a spot in the nursing home!
I'm sure if there was a lower cost replacement for cats, people would be clamouring for it.
By the way, never in over 20 years have I had to buy a catalytic converter. With a properly maintained engine, they last a very long time.
Engine tuning has very little to do with it. The cat does the lions share of emissions reduction. And the notion that it "strangles" is plain false. You would not notice the difference if you cut it out. Watch Glen's video above and educate yourself.
thanks for your input, i sit corrected
You're welcome. Glad I could add to your understanding. Cat.Cons are actually one of the few emissions components that work well. It's failures like cylinder deactivation and flex fuel that piss me off.
you mean like that 4-6-8 caddy debacle? i remember that
Exactly. And 40 years later, they still can't get it right.
It's the catalytic converters that permit today's engines to be as clean as they are. In fact since the advent of 3-way catalysts, pollutants have been reduced to the point where further cleanup is well into diminishing returns. Young people in the U.S. today have never really experienced air pollution like we had 50+ years ago.
These young people are fortunate to have never sat at a stop light back in the sixties and had to smell all the exhaust fumes from the cars around them.
I am fortunate, but every so often I sit behind car from the sixties and I get a taste.
Visit most ‘developing’ nations & these exhaust fumes are still very much present..
The actual purpose that catalytic converters serve is to add about $1000 to the price of the vehicle and to kiss the EPA's ass. Anything after that is debatable.
C'mon Joe - no sense of humor??
did I miss the punchline? {black}:idontknow:
Yep. Small aircraft have CO detectors for this very reason ... no cats means sleepy time for pilots if it build up @mittegag
They do actually serve an actual purpose which is keeping the NOx emissions as low as possible. But these days, I see a lot of cats being stolen so I start to think that they also do serve another purpose which is making money. I start to not believe in cats at all. The main reason why air pollution happened in the early days is that the factories, industries, electricity generators, and so on emit tons of smoke into the air. Those emissions combined with the emission of NOx from automobile makes it even worse. Yet, the gov. still doesn't do anything to those factories at all but, they make strict emissions standards for automobiles.
So because you can't keep your car safe, you should be able to pollute. Interesting logic.
Can you explain how the government "doesn't do anything about factories". Any data at all?
It looks to me like most of those smoggy old factories are gone. I can name several in my area.
Regulations are not perfect, but we have made big strides.
Multiple laws have been put in place :
Acid Rain Program
Clean Air Act
Cross-State Air Pollution Rule
Clean Power Plan
and on and on ...
many online articles you can read about changes that have been made.
If cats are so great, how come piston powered aircraft don't have them?
And what about jet airliners? Don't they spew tons of pollutants?
And ocean liners?
The list goes on.
There are presently one and a half billion motor vehicles operating in the world today.
How many small aircraft and ocean liners?
Yes, airliners pollute, but they also haul over 400 humans for thousands of miles in a short amount of time. And they do it 40,000 ft in the air. Do you fly every day? So if everyone one of those people drove one car for that same distance in a busy city , that's better? Should we stop air travel?
And so because we can't put cats on these machines, we should stop putting them on cars?
I don't think you've really thought this through.
Please go on ... what's next on your list?
B.S.
What a delightful insight. So do you have any actual arguments, or are we just going to shout two-word vulgarities in large bold text? because I sincerely hope that's not the kind of forum you want.