You're too stupid to... own a diesel small truck

[Bick]

A 55 hasn't come my way that's all. Maybe next time.

You will probably have to go to it.

[Popeye the Sailor]

The current emission equipment required for US diesels, and recently European diesels, is a real pain in the ass. The requirements of the diesel particulate filter in particular really impact how they operate and their efficiency. The Urea injection systems are more just a pain in the ass. Nevermind the cost, as the guy in the article mentions. Hopefully the systems become less of an issue as the manufacturers get better and making them.

That's because diesel emissions are incredibly bad for your lungs and the enviroment-far worse than gasoline.

[Zaster]

What he said.
15 times as many harmful particles are emitted by diesel engines vs. gasoline engines.

[Triple J]

Not quite as simple as that regarding the environment. Diesels may emit more particulates and NOx, but they generally get about 30% better gas mileage (so use less oil), and emit less CO2. Diesel motors also last a lot longer than gasoline engines, so a much better life cycle.

Regardless, it'll be nice when the manufacturers get better at the emissions side of things for diesel...and it seems they're getting better every year.

[Popeye the Sailor]

Not quite as simple as that regarding the environment. Diesels may emit more particulates and NOx, but they generally get about 30% better gas mileage (so use less oil), and emit less CO2. Diesel motors also last a lot longer than gasoline engines, so a much better life cycle.

Diesel is about 8-17% denser than gasoline (depends on summer or winter blend of gas).
The apparent efficiency of diesel engines is in part due to the fact that efficiency is characterized per volume unit (mpg), not per mass unit (miles per kg). When you think about the actual mass of fuel burned, the efficiency difference between gas and diesel isn't 30-35%, but more like 18-27%.

Please see the attached chart:



The attached figure is from a comprehensive 2003 DOE study, and clearly shows that diesel emits more submicron particles. Not to mention substantially more coarse particles. That study concluded that gasoline engines only have the potential to match diesel for the emission of PM2.5 when at high speed under heavy load, or when worn and burning oil.

Additionally, what were are talking about here is primary aerosol, i.e. particles formed at the tailpipe. Secondary aerosols that are formed in situ by the atmospheric oxidation of gaseous compounds tend to occupy the respirable size mode exclusively. In other words, particles that coalesce as gases react in the atmosphere are about 99% PM2.5, and therefore easily penetrate the deep lung.

Diesel has a MUCH greater contribution to secondary aerosol than gasoline because diesel hydrocarbons are larger and have lower volatility than gasoline. Therefore, it takes much less atmospheric oxidation to initiate the particle formation process. Additionally, the large primary particles emitted by diesel engines contain heavy hydrocarbons that evaporate as the particles dissipate. Those hydrocarbons have an extremely high tendecy to form secondary aerosol. Google the research of Spiros Pandis if you want to learn about this process in detail.

[Bick]

Aren't the newer diesels (like the bluetec and the BMW) supposed to be much cleaner burning?

[Popeye the Sailor]

Aren't the newer diesels (like the bluetec and the BMW) supposed to be much cleaner burning?

They are, but they end up using the very systems that were being complained about.

[Bick]

They are, but they end up using the very systems that were being complained about.

There is no winning with anything.

[Kev M]

And the new systems make them less efficient, more costly to run, and less reliable.

Check out some parts replacement costs, into the thousands of dollars for duffle l single fuel system components.

(And to be clear I am, or at least was, a fan of diesel, nor am I a Luddite. I don't typically shy away from new, even first model year runs. And I tend to be hippie-like at keeping my emissions equipment intact/operable). I just really have to question the cost vs benefit of a non-commercial diesel in the US currently (if you're not regularly towing large loads).

[ducatiz]

Using ULSD fuel, the largest particulate is just carbon.  Not co2, but plain old C.  It does irritate asthma, but it's also easily dealt with.

None of the systems for scrubbing are that old.  In 5 years diesel exhausts will be nearly harmless.

The net cost to fuel economy is small too.  My 2005 golf tdi would get 52 mpg highway on my trips to Annapolis.   My 2009 jetta - with a bigger engine and heavier frame - gets a hair under 50mpg.

And that's with 40 hp more.

[Triple J]

There is no winning with anything.

Exactly

[Monsterlover]

Diesel is about 8-17% denser than gasoline (depends on summer or winter blend of gas).
The apparent efficiency of diesel engines is in part due to the fact that efficiency is characterized per volume unit (mpg), not per mass unit (miles per kg). When you think about the actual mass of fuel burned, the efficiency difference between gas and diesel isn't 30-35%, but more like 18-27%.

Please see the attached chart:



The attached figure is from a comprehensive 2003 DOE study, and clearly shows that diesel emits more submicron particles. Not to mention substantially more coarse particles. That study concluded that gasoline engines only have the potential to match diesel for the emission of PM2.5 when at high speed under heavy load, or when worn and burning oil.

Additionally, what were are talking about here is primary aerosol, i.e. particles formed at the tailpipe. Secondary aerosols that are formed in situ by the atmospheric oxidation of gaseous compounds tend to occupy the respirable size mode exclusively. In other words, particles that coalesce as gases react in the atmosphere are about 99% PM2.5, and therefore easily penetrate the deep lung.

Diesel has a MUCH greater contribution to secondary aerosol than gasoline because diesel hydrocarbons are larger and have lower volatility than gasoline. Therefore, it takes much less atmospheric oxidation to initiate the particle formation process. Additionally, the large primary particles emitted by diesel engines contain heavy hydrocarbons that evaporate as the particles dissipate. Those hydrocarbons have an extremely high tendecy to form secondary aerosol. Google the research of Spiros Pandis if you want to learn about this process in detail.

[Triple J]

The attached figure is from a comprehensive 2003 DOE study, and clearly shows that diesel emits more submicron particles.

Interesting info. Understood that diesels emit more particulates.

Being a 2003 study it didn't consider ultra low sulfur diesel fuel, correct? ULSD didn't start really being used until 2006. ULSD contains about 3% of the sulfur that the previous grade contained, and the sulfur is what is responsible for the majority of the particulates, so the chart is a bit out of date?

For the record, I'm not against the cleaner diesel technologies. I just wish the diesel particulate filter (DPF) systems were more user friendly. For instance, why flood the exhaust stream with raw fuel to complete the regen cycle? Why not just do it with a second dedicated alternator? Nevermind the sensor problems that many experience. Anyway, I'm sure the systems will get better over the next few years.

[duccarlos]

My head hurts

[Kev M]

The net cost to fuel economy is small too.  My 2005 golf tdi would get 52 mpg highway on my trips to Annapolis.   My 2009 jetta - with a bigger engine and heavier frame - gets a hair under 50mpg.

And that's with 40 hp more.

That sounds optimistic, but I'm contrasting it with not my own, but my little-brother's experience.

He drank the diesel cool-aide a couple of years ago, got rid of his BMWs, Mini's, etc, bought a F250, Jetta TDI, Golf TDI.

I was hoping he would chime in on this thread (he's got a new 796 and is a member here too), but he must be preoccupied.

Anyway, we've talked at some length about the industry wide impact of the new systems on efficiency, at least on the truck side. Though some of that might be the result of the accompanying power wars too.

He also says neither his Jetta or Golf are as efficient as prior models.

<shrugs>

I was seriously considering the Grand Cherokee with the Morini diesel, but another $5k for initial cost, the cost of DEF refills, the approximately $1/gallon higher cost of fuel.

The 4wd gas V6 gets 17/24 while the diesel gets 21/28.

And FWIW, in the real world our gas V6 is getting more like 18-19 (sometimes 20)/22-25 (and as high as 26).

I just don't see the payback.