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  #1  
Old 10-14-2008, 03:39 AM
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unrealistic pollution scores

is this really true? how can a car that almost gets 40mpg rank as a 1?


http://www.fueleconomy.gov/Feg/byfuel/Diesel2008.shtml
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  #2  
Old 10-14-2008, 04:53 AM
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Yea, those scores totally don't make any sense...it says that a 2005 CL500 with a 5L V8 gets a 7!!!!
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  #3  
Old 10-14-2008, 05:07 AM
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Just another way that america thinks that diesel is dirty.
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  #4  
Old 10-14-2008, 05:45 AM
ForcedInduction
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Diesel emissions are evaluated per gallon consumed, g@ssers are per mile driven.

Just another example of why the EPA needs a complete overhaul and the CARB needs to be outlawed.
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  #5  
Old 10-14-2008, 02:07 PM
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Diesel engines do inherently put out very high levels of NOx (relative to gasoline engines) and NOx's are the worst offenders when is comes to generating smog. If you are worried about your contribution to smog driving around in a 'dirty' diesel, make sure that at least your EGR is connected......lower combustion temps reduce NOx and that is why the EGR is there. On the plus side for diesels is greater efficiency so less fuel use and a smaller "carbon footprint"....but that doesn't necessarily mean less pollution of all types.

I don't think the EPA is biased against diesels, I think they just present the facts about diesel emissions but without painting an entire picture. The offset for drivers of old Benz diesels I think is how much pollution we are all preventing from being created by driving these cars that last 30+ years. No metal smelters belching who knows what all making steel to build cars on my account, no power plants burning coal and make electricity to run those smelters and those car factories on my account.
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  #6  
Old 10-14-2008, 02:49 PM
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Or just add an I/C and 3" exhaust; and then leave the fuel at the normal "low" setting
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  #7  
Old 10-14-2008, 05:44 PM
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Quote:
Originally Posted by Simpler=Better View Post
Or just add an I/C and 3" exhaust; and then leave the fuel at the normal "low" setting
Oh how I would love to turbo my 2.5l, better gas mileage and a waay cooler sounding motor.. mmmm turbo drool
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But then I don't worship the engine or view it as something sacred to be protected, babied, and treasured forever either. It is a machine - a fine machine to be sure - but still just a machine, and it is meant to be used. I specifically bought a Mecedes IDI because they are about THE most tolerant engine there is when it comes to alternative fuels, and that's what I wanted - to be able to use alternative fuels.
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  #8  
Old 10-14-2008, 06:59 PM
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The EGR on the OM617 just clogs the intake w/soot, resulting in richer running and prodution of even more soot.

How does that lower NOx emissions?
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  #9  
Old 10-14-2008, 07:52 PM
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NOx has nothing to do with soot. It is a result of high combustion temperature. Adding a bit of inert gas to the intake is a proven method of reducing combustion temperature, and thus NOx formation.
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  #10  
Old 10-14-2008, 08:23 PM
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Those pollution scores don't include greenhouse gas emissions (related to fuel economy) which are listed separately. Also the EPA pollution scale is based on the typical gasoline exhaust profile which makes it difficult for any diesel except the new generation of clean diesels to score high. For example, an older diesel may do pretty well on HC and CO emissions and keep up with the best of gassers, but because of higher PM and NOx emissions it gets knocked down to the bottom of the scale. You could say the scale is a bit biased.
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  #11  
Old 10-14-2008, 08:26 PM
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Quote:
Originally Posted by harpua00 View Post
NOx's are the worst offenders when is comes to generating smog..
NOx need HC's (mainly from gassers) to form smog. Some studies have even suggested that gasoline engines contribute more to smog than diesels. I think the main problem with diesels has historically been the soot, but that has gone down over the years, and with the latest generation of engines it's no longer an issue at all.
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  #12  
Old 10-14-2008, 08:26 PM
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Its a trade off. The EGR lowers NOx at the expense of higher HC and soot emissions.

Thats why you never see modern Diesels with just a particulate filter or just a NOx scrubber. Particulate filters increase NOx through hotter combustion (harder working engine and high EGTs to burn off the soot) and NOx scrubbers increase soot by restricting the engine's breathing.

Diesels have always been seen as "dirty" because the exhaust can sometimes be seen. Just today I was caught behind a school bus that was puking thick black smoke...
Soot is not a bad emission, almost all of it settles back to the ground and the particles are too big to get caught in the lungs (Easily coughed up). Particulate filters are "feel good" emissions devices, if it looks clean it must be clean. Problem is, they make things worse by increasing the number of micro soot particles that can get stuck in the lungs!

Lock yourself in a garage with a running g@sser and you'll soon be taking a very long nap. Lock yourself in a garage with a running Diesel and you'll just get a really nasty headache and sore eyes.

Last edited by ForcedInduction; 10-14-2008 at 08:35 PM.
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  #13  
Old 10-14-2008, 08:34 PM
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Quote:
Originally Posted by ForcedInduction View Post
Its a trade off. The EGR lowers NOx at the expense of higher HC and soot emissions.

Thats why you never see modern Diesels with just a particulate filter or just a NOx scrubber. Particulate filters increase NOx through hotter combustion (harder working engine and high EGTs to burn off the soot) and NOx scrubbers increase soot by restricting the engine's breathing.
To my knowledge EGR does lower HC emissions as well because as the exhaust is recirculated (the whole idea behind EGR) most remaining HC's in the exhaust are burned as well. EGR does lead to more soot being dumped in the oil, but not necessarily to the atmosphere. EGR has been around for about 25 years but particulate filters are just now starting to show up.
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  #14  
Old 10-14-2008, 08:39 PM
ForcedInduction
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Originally Posted by DieselAddict View Post
EGR has been around for about 25 years but particulate filters are just now starting to show up.
Not really. Mercedes was the first manufacturer in the world to introduce particulate filter systems for cars, in 1985 (Known as the TrapOx). They abandoned them in 1987 because the technology to control the regeneration cycle wasn't available.
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  #15  
Old 10-14-2008, 08:39 PM
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Quote:
Originally Posted by ForcedInduction View Post
Soot is not a bad emission, almost all of it settles back to the ground and the particles are too big to get caught in the lungs (Easily coughed up). Particulate filters are "feel good" emissions devices, if it looks clean it must be clean. Problem is, they make things worse by increasing the number of micro soot particles that can get stuck in the lungs!

Lock yourself in a garage with a running g@sser and you'll soon be taking a very long nap. Lock yourself in a garage with a running Diesel and you'll just get a really nasty headache and sore eyes.
I don't know about diesel soot being easily coughed up, but it's true that it's the small particles that are most dangerous to lungs. Particulate filters don't increase their quantity, only their ratio in the exhaust, a major difference. Overall they're still a good idea, no doubt.

Yup, an older running gasser in a closed garage will kill you in no time because of CO, but personally I prefer to leave the garage door open and stick the car's ass out if I have to run it regardless of what fuel it's burning.
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