Why are turbo engines less polluting?
02-01-2018, 01:24 AM
#31
Rennlist Member
That's not the case in LA, New York, Seattle, Las Vegas, Dallas, Houston, Chicago, Miami, Orlando, and most of the big cities.
Think the only place such driving habits is in abundance are in towns with a population under 1000 and 999 of those are super seniors. That last person is just a passing by.
Do you realize how SLOW a car acceleration if it's only using 20% or less throttle? 0-60 would take 20+ seconds in pretty much any car.
02-01-2018, 04:45 AM
#32
RL Community Team
Rennlist Member
Rennlist Member
Depends on where you live.
That's not the case in LA, New York, Seattle, Las Vegas, Dallas, Houston, Chicago, Miami, Orlando, and most of the big cities.
Think the only place such driving habits is in abundance are in towns with a population under 1000 and 999 of those are super seniors. That last person is just a passing by.
Do you realize how SLOW a car acceleration if it's only using 20% or less throttle? 0-60 would take 20+ seconds in pretty much any car.
That's not the case in LA, New York, Seattle, Las Vegas, Dallas, Houston, Chicago, Miami, Orlando, and most of the big cities.
Think the only place such driving habits is in abundance are in towns with a population under 1000 and 999 of those are super seniors. That last person is just a passing by.
Do you realize how SLOW a car acceleration if it's only using 20% or less throttle? 0-60 would take 20+ seconds in pretty much any car.
02-01-2018, 08:17 AM
#33
1st Gear
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Read this a few years ago ... similar type of nonsense from automakers.
The Catalytic Converter Conspiracy
If you drive an American automobile of a later year than 1975, which should be about everyone in America, it has a catalytic converter. Unless it's older than 1984 in which case you can cut the sucker off, and pitch it. The catalytic converter or "cat" for short was first thought of in the early 1950s by a french engineer living in L.A. named Eugene Houdry. He was tired of all the smog, and worked in catalytic oil refining. The first production cats weren't introduced until 1973 when lead was taken out of gasoline as an anti-knock agent, and some other guys fussed around with the design, and improved it. Lead gunked up the converter. By 1975 all vehicles had to have a cat from the factory, and by 1985 it was a crime to take it off your vehicle if it was built in that year, or later.
The idea behind the cat is to burn unburned hydrocarbons(fuel molecules) left over from the combustion cycle. It wasn't really too bad of an idea for the time because cars were carbureted then, and the fuel mix ratio was just set to the best compromise for most conditions. If it got cold, or you had a big drop in altitude it would be a little lean, if it got hot, or you went up into the mountains it would be a little rich. Most of them were set on the rich side because a spark ignition engine runs better a little rich than it does too lean. So this meant unburned fuel coming out the tail pipe. The cat was supposed to burn this extra gas and clean up the emissions. Good idea right?
Maybe sort of at first. The biggest problem with early converters is that they took a long time to get hot, and they had a problem staying hot enough to burn the fuel all the time because the carburetor wasn't always that far off, and sometimes was too lean to keep the cat hot, but rich enough to still waste some gas. Enter the smog pump. It blew air into the cat like a blast on a furnace to keep it hot, and the carburetors were intentionally set even richer to make sure they wasted enough fuel to keep the cat hot. Plus the smog pump pulled about 5 horsepower. So now we are wasting fuel to support a device to catch wasted fuel, brilliant. Now I'm sure all the oil companies were just heart broken that every single car on the road was going to have to consume about 30% more fuel to catch any incidental unburned fuel that might escape due to the carburetion system.
Then in the mid 80s we started getting good at fuel injection, and now we can control how much fuel the engine gets at any time. Coincidentally about the same time the feds mandate the catalytic converter to be on all engines about 25HP all the time, for all time, and with no exceptions, EVER. A little convenient? Seeing as there should be very little waste fuel now that we can accurately meter the fuel to the engine's needs. Your modern vehicle's computer is now so sophisticated that it can vary the pulse of every injector by 1/100th of a gram every single rotation of the engine. There is absolutely NO reason whatsoever for a modern vehicle to have a catalytic converter. Accept that it takes about 15%-20% more of your fuel(read money) to keep it hot, and running. Better than the 30% or more from days of yore, but still very wasteful. Not to mention the less than beneficial side effects produced by the cat. Like acid rain from hydrogen sulfide.
Anyone with a moderate understanding of combustion theory, and an understanding of engine control systems knows that a properly electronically tuned engine burns many times cleaner than the federally mandated system. Some european contries won't even allow california smog equipped vehicles in their country because they are so dirty. At our current level of technology it is abundantly apparent that it has nothing to do with clean air, and everything to do with $$$.
The Catalytic Converter Conspiracy
If you drive an American automobile of a later year than 1975, which should be about everyone in America, it has a catalytic converter. Unless it's older than 1984 in which case you can cut the sucker off, and pitch it. The catalytic converter or "cat" for short was first thought of in the early 1950s by a french engineer living in L.A. named Eugene Houdry. He was tired of all the smog, and worked in catalytic oil refining. The first production cats weren't introduced until 1973 when lead was taken out of gasoline as an anti-knock agent, and some other guys fussed around with the design, and improved it. Lead gunked up the converter. By 1975 all vehicles had to have a cat from the factory, and by 1985 it was a crime to take it off your vehicle if it was built in that year, or later.
The idea behind the cat is to burn unburned hydrocarbons(fuel molecules) left over from the combustion cycle. It wasn't really too bad of an idea for the time because cars were carbureted then, and the fuel mix ratio was just set to the best compromise for most conditions. If it got cold, or you had a big drop in altitude it would be a little lean, if it got hot, or you went up into the mountains it would be a little rich. Most of them were set on the rich side because a spark ignition engine runs better a little rich than it does too lean. So this meant unburned fuel coming out the tail pipe. The cat was supposed to burn this extra gas and clean up the emissions. Good idea right?
Maybe sort of at first. The biggest problem with early converters is that they took a long time to get hot, and they had a problem staying hot enough to burn the fuel all the time because the carburetor wasn't always that far off, and sometimes was too lean to keep the cat hot, but rich enough to still waste some gas. Enter the smog pump. It blew air into the cat like a blast on a furnace to keep it hot, and the carburetors were intentionally set even richer to make sure they wasted enough fuel to keep the cat hot. Plus the smog pump pulled about 5 horsepower. So now we are wasting fuel to support a device to catch wasted fuel, brilliant. Now I'm sure all the oil companies were just heart broken that every single car on the road was going to have to consume about 30% more fuel to catch any incidental unburned fuel that might escape due to the carburetion system.
Then in the mid 80s we started getting good at fuel injection, and now we can control how much fuel the engine gets at any time. Coincidentally about the same time the feds mandate the catalytic converter to be on all engines about 25HP all the time, for all time, and with no exceptions, EVER. A little convenient? Seeing as there should be very little waste fuel now that we can accurately meter the fuel to the engine's needs. Your modern vehicle's computer is now so sophisticated that it can vary the pulse of every injector by 1/100th of a gram every single rotation of the engine. There is absolutely NO reason whatsoever for a modern vehicle to have a catalytic converter. Accept that it takes about 15%-20% more of your fuel(read money) to keep it hot, and running. Better than the 30% or more from days of yore, but still very wasteful. Not to mention the less than beneficial side effects produced by the cat. Like acid rain from hydrogen sulfide.
Anyone with a moderate understanding of combustion theory, and an understanding of engine control systems knows that a properly electronically tuned engine burns many times cleaner than the federally mandated system. Some european contries won't even allow california smog equipped vehicles in their country because they are so dirty. At our current level of technology it is abundantly apparent that it has nothing to do with clean air, and everything to do with $$$.
Firstly a catalytic converterdoesn't burn fuel(wtf honestly), it doesn't burn anything actually.
The only things it does are creating a reaction that reduces nitrogen oxides to nitrogen and carbon dioxide, an oxidation reaction of carbon monoxides to carbon dioxide, and an oxidation reaction of unburned hydrocarbons to carbon dioxide and water.
02-01-2018, 08:38 AM
#34
Unfortunately it's not how it works
Firstly a catalytic converterdoesn't burn fuel(wtf honestly), it doesn't burn anything actually.
The only things it does are creating a reaction that reduces nitrogen oxides to nitrogen and carbon dioxide, an oxidation reaction of carbon monoxides to carbon dioxide, and an oxidation reaction of unburned hydrocarbons to carbon dioxide and water.
Firstly a catalytic converterdoesn't burn fuel(wtf honestly), it doesn't burn anything actually.
The only things it does are creating a reaction that reduces nitrogen oxides to nitrogen and carbon dioxide, an oxidation reaction of carbon monoxides to carbon dioxide, and an oxidation reaction of unburned hydrocarbons to carbon dioxide and water.
02-01-2018, 01:33 PM
#36
Rennlist Member
That one push of the accelerator in 1st/2nd gear will be more than 20% throttle. Repeat that for 30 mins doing it every 15-20 seconds.
02-01-2018, 03:16 PM
#37
Burning Brakes
Just to go off topic a bit, this Auto Start Stop thing that the bureaucrats came up with is doing the opposite effect in terms of emissions. When my car is idling at stops, I don't smell anything. As soon as it kills the engine and starts again, I smell it every time. My guess is the cats when "cold" does not perform well. How is that helping curb pollution?
02-01-2018, 03:22 PM
#38
Three Wheelin'
It burns less fuel while it's off so less CO2 for sure. Whether savings on other emissions are party or fully offset by the cold cat I don't know.
Cars now have significantly beefed up starter motors that can withstand continual starting. These are of course much heavier, which is one of the reasons the lightweight Porsches don't have them.
Cars now have significantly beefed up starter motors that can withstand continual starting. These are of course much heavier, which is one of the reasons the lightweight Porsches don't have them.
02-02-2018, 12:49 AM
#39
RL Community Team
Rennlist Member
Rennlist Member
If you are stuck in traffic and you don't accelerate briskly, the car on the left and the car on the right WILL cut right in front of you and take your 'space'.
That one push of the accelerator in 1st/2nd gear will be more than 20% throttle. Repeat that for 30 mins doing it every 15-20 seconds.
That one push of the accelerator in 1st/2nd gear will be more than 20% throttle. Repeat that for 30 mins doing it every 15-20 seconds.
My point here isn't really to debate how people drive, but just to note that EPA testing of emissions for FI v. NA cars are not that far off.
(Also, back to an earlier post, I actually think people who live out in less populated areas are the ones who really get to go WOT on their cars, be they FI or NA. Luck them.
)
02-02-2018, 07:00 AM
#40
My 3.8 997.2 Turbo and 4.0 991.2 GT3 both have +/- 500HP. I realise there are many variables at play but I thinks its a fairly appropriate real world comparison of smaller displacement turbo vs higher displacement NA for the same HP. The turbo, even with its older tech, gets better overall MPG than the GT3 when driven in a similar manner (mixture of around town to spirited mountain roads driving).
02-02-2018, 09:48 AM
#41
Rennlist Member
Turbo charging produces higher combustion temperatures and pressures thereby providing more complete burning and leaving fewer unburned hydrocarbons as pollutants.
PS - You did not say anything about polluting being heat or CO2, CO which are byproducts but not what you meant
PS - You did not say anything about polluting being heat or CO2, CO which are byproducts but not what you meant
02-02-2018, 12:25 PM
#42
Rennlist Member
Turbo charging produces higher combustion temperatures and pressures thereby providing more complete burning and leaving fewer unburned hydrocarbons as pollutants.
PS - You did not say anything about polluting being heat or CO2, CO which are byproducts but not what you meant
PS - You did not say anything about polluting being heat or CO2, CO which are byproducts but not what you meant
02-02-2018, 01:32 PM
#43
Instructor
real world...
I have been saying this since the big VW emissions scandal. The turbo cars are the mechanical equivalent of cheating emissions tests and the mfr know it. For the testing conditions, the turbos will be more efficient. For real life driving, it could actually be the opposite for in town driving.
A big ding in fuel economy is sitting in traffic - so naturally a smaller disp engine will use less gas at idle, and if someone drives like my wife, they never use more than 50% throttle anyway...
The Mazda SkyActiv engine is very interesting - approx 30% better gas mileage than regular gasoline engines with same displacement. They run diesel like compression ratios
02-02-2018, 02:28 PM
#44
Rennlist Member
Except that cars I drive now definitely get better MPG than my cars 30 years ago. Los Angeles air is significantly better than it was 30 years ago so they're doing something right.
A big ding in fuel economy is sitting in traffic - so naturally a smaller disp engine will use less gas at idle, and if someone drives like my wife, they never use more than 50% throttle anyway...
The Mazda SkyActiv engine is very interesting - approx 30% better gas mileage than regular gasoline engines with same displacement. They run diesel like compression ratios
A big ding in fuel economy is sitting in traffic - so naturally a smaller disp engine will use less gas at idle, and if someone drives like my wife, they never use more than 50% throttle anyway...
The Mazda SkyActiv engine is very interesting - approx 30% better gas mileage than regular gasoline engines with same displacement. They run diesel like compression ratios
If it weren’t for safety systems that have added a lot of weight over the 30 years, I’d bet today’s cars’ MPG rating would be far higher than they are now.
02-02-2018, 02:39 PM
#45
I will say this after spending a lot of time driving the 9A1 3.4L base Carrera 991.1 engine (C2), and now with the 9A2 3.0L base Carrera 991.2 engine (*with AWD*) in my C4.
My 3.0L engine is averaging 15 MPG for what is mostly city driving here in Honolulu. Averaging 15 MPG with the new turbo motor, and I averaged 18 MPG with the older 3.4L..... I thought that AWD might be less efficient but the AWD system doesn't send power to the front wheels all the time but only when needed....
Likely the result might be different if I was on the mainland with mostly freeway/highway driving, but for city I am getting worse MPG with the new 3.0L
My 3.0L engine is averaging 15 MPG for what is mostly city driving here in Honolulu. Averaging 15 MPG with the new turbo motor, and I averaged 18 MPG with the older 3.4L..... I thought that AWD might be less efficient but the AWD system doesn't send power to the front wheels all the time but only when needed....
Likely the result might be different if I was on the mainland with mostly freeway/highway driving, but for city I am getting worse MPG with the new 3.0L