Poll for Americans: What about Diesel engines?

[jamesqf]

Originally Posted by Big Dave

So some people say that infinitesimal benefits in air quality for the benefit of a very small subset of the population outweigh a large improvement in MPG for everybody.

Seems like I've heard that line before. Back in the '70s, when Detroit kept saying that their gasoline engines couldn't possibly meet emissions standards (even the lesser ones of those days) without costly & complex air injection pumps and other costly economy & performance-robbing add-ons. Then along came Honda with their CVCC engine, other companies (not often American ones, alas) introduced things like variable valve timing & electronic fuel injection, and all of a sudden their engines were getting lower emissions AND better performance.

That makes improved MPG Mission: Impossible unless you force people to drive small cars they don't want.

Or unless someone comes up with a source of the small cars some of us want, which Detroit refuses to build. Even at the height of the SUV craze, Honda, Toyota, and all the rest were making good profits building small cars. How'd they manage that if people didn't want them?

[cfg83]

roflwaffle -

Originally Posted by roflwaffle

That would be great if everyone just stayed in their respective areas and never traveled or sold their vehicle to anyone else, but unfortunately they do. In specific instances, long haul trucking for example, limiting use for a patchwork of emissions regs is pointless.

What if you had a GPS integrated with a map of emissions compliance requirements inside the car computer? Or, instead of a map, an "auto download" of emissions requirements based on location? In this situation, the drivetrain would "comply as needed" with each state's emissions laws. You would have the "cost of maximum compliance", but you could also have the "best MPG" in low density (i.e. agricultural) areas. GM already has OnStar, so the hardware is already in place.

PS - I'm not sure I would advocate this is a real-world solution, but I think it's technically possible.

CarloSW2

[hal9999]

As long as mankind will use fossil energy the pollution problem will remain,
and we will stay trapped in the following scheme:

1. Pollution
2. Anti-pollution laws
3. Newer technologies
4. Repeat point nr. 1

Or with the words of Newton’s third law:
To every action there is an equal and opposite reaction (and vis versa).

Many call this progress. Me included. Although I don’t like to be patronized.
Now how these anti-pollution laws have to be applied is another question.

To the believe that pollution is a static or local problem, IMHO Chernobyl proved the contrary.

[roflwaffle]

Originally Posted by cfg83

What if you had a GPS integrated with a map of emissions compliance requirements inside the car computer? Or, instead of a map, an "auto download" of emissions requirements based on location? In this situation, the drivetrain would "comply as needed" with each state's emissions laws. You would have the "cost of maximum compliance", but you could also have the "best MPG" in low density (i.e. agricultural) areas. GM already has OnStar, so the hardware is already in place.

PS - I'm not sure I would advocate this is a real-world solution, but I think it's technically possible.

CarloSW2

Since there are only two standards I'm aware of, Fed and CARB, I don't see why it wouldn't be possible, but both require DFPs so it's not like there would be less equipment, and significantly better mileage. We're talking about a year or few of lag between Fed and CARB emissions standards. What's gotta happen is the advances seen in gasser emissions management for diesels. They're where gassers were in the 70s, but fortunately they have a bit more in the way of tech to apply. Unfortunately, this means we just see higher tech cludges, instead of research on comprehensive emissions control strategies, like we see in gassers these days.

[Big Dave]

Jamesqf posted;

“…introduced things like variable valve timing & electronic fuel injection, and all of a sudden their engines were getting lower emissions AND better performance.”


Big Dave says:

“All of a sudden” in reality means a twenty to thirty year time frame. When the first anti-pollution regs came out in 1973, car performance fell off the cliff. It began to come back in the mid 90s and had caught up to 1970 levels by the early twenty-first century.

Yup. Today’s cars are better than those of the 1960s – a 2004-2006 GTO will run off and hide from the classic Goat and stop, and handle, and even get better mileage – but we were in the wilderness for a quarter of a century. “Sudden” is not a word that fits this process.

[roflwaffle]

Originally Posted by Big Dave

Yup. Today’s cars are better than those of the 1960s – a 2004-2006 GTO will run off and hide from the classic Goat and stop, and handle, and even get better mileage – but we were in the wilderness for a quarter of a century. “Sudden” is not a word that fits this process.

In all fairness, diesels have a thirty year tech head start compared to gassers in the 70s, now manufacturers just need to develop that tech. It's not even as if all manufacturers can't design an emissions system for their life. For instance VW managed to put out a cleaner, quieter, more powerful vehicle that was just as efficient as the older version. The 2003 has a relatively primitive emissions system w/ no DPF, and just a two way cat, while the 2008 version has a DPF and NOx storage catalyst.

The fact that a foreign auto company can do so much better at roughly the same price, boosting performance as well keeping emissions (well past truck requirements btw) down while FE is almost identical indicates that it isn't even diesel emissions tech that's behind the ball so much as domestic manufacturer's implementations of it.

[jamesqf]

Originally Posted by Big Dave

“All of a sudden” in reality means a twenty to thirty year time frame. When the first anti-pollution regs came out in 1973, car performance fell off the cliff. It began to come back in the mid 90s and had caught up to 1970 levels by the early twenty-first century.

Maybe, if you're just looking at what came out of Detroit. I wouldn't know about that, 'cause after that Vega I wasn't real interested in buying an American car. But I had a couple of 80-84 Subarus: flat 4, not a lot of extra emissions equipment, and they got decent mpg considering the amount of time I spent in 4WD, driving up mountains in snowstorms - and pulling the occasional SUV out of snowbanks :-). The '85 CRX I had likewise didn't have a lot of power-robbing extras, and would get 40+ mpg even with the way I drove it. So it seems the Japanese, at least, managed to get their emissions control act together in fairly short order.

[ConnClark]

It amazes me that so many people here have the attitude that if it can be done on gasoline engine you should be able to do the same on a diesel.

There are substantial differences in the way they operate and this causes a different set of problems. For one the exhaust temperatures of a diesel under typical operation are vastly lower than that of a gas engine. This is partly due to the excess air that diesels run with but its also due to the fact that the diesel cycle allows more energy to be extracted by the piston. This lower exhaust temperature makes it hard for DPFs and catalysts to function.

Excessive back pressure increases PM emissions the same way that excessive EGR does because it doesn't allow for proper clearance of combustion gasses in the cylinder before the next intake charge (Note: A turbo doesn't create this problem because the back pressure it creates forces more fresh air into the cylinder on the intake stroke negating the effect ). This effect causes a DPF filter to plug up more because it has to deal with even more PM. On the 80's California emissions Mercedes with DPFs this often accelerated to a run away condition. This run away plugging led to cracked heads, destroyed turbos, and in some cases a car that wouldn't run at all. On a gasoline engine this isn't an issue since any fuel brought into the cylinder comes with a stochiometric amount of air to burn it.

The main reductions in emissions to the modern diesel engines has been due to the growth of computing power to allow engineers to actually simulate engines. The complex interaction and combustion of fuel mixing with air in a dynamically challenging chamber is much more difficult than simulation of a uniform mixture combusting like in a gas engine. My lap top has more computing power than the computing power of Mercedes Benz's computers put together when my car was built. As such a modern diesel engine will emit far less pollution with no pollution controls than my 1985 california emissions engine with all of its controls.

I fear that as long as a diesel engine maintains better mileage than a gas engine the EPA and CARB will see that as justification to impose stricter emissions controls on diesels regardless of whether it makes any difference in the big picture of things or not. Most of the diesel emissions today are made by vehicles that are 20 years or older. Due to the longevity of diesel engines these vehicles last longer than gas powered ones so it just takes longer for accidents and wear and tear to take them out of the picture. Regardless of how clean you make the new ones its not going to make a big dent in diesel pollution for a while.


Should old diesels be banned? IMHO no! The gov't said these vehicles were good enough when they were sold and the gov't should stick to its word. Maybe manufacturers should be able to sell a diesel with no emissions controls for every old polluting diesel they take off the streets. That is a far better and possibly cheaper option than adding a DPF to modern vehicles since you can pick up an old diesel for less than $3000.

[jamesqf]

Originally Posted by ConnClark

It amazes me that so many people here have the attitude that if it can be done on gasoline engine you should be able to do the same on a diesel.

I think most of us are probably just going on past performance. We've had several decades of listening to Detroit say "but we can't possibly do that", where "that" seems to be anything but build bigger cars with worse fuel economy. So why should we believe them this time around?

[roflwaffle]

Originally Posted by jamesqf

I think most of us are probably just going on past performance. We've had several decades of listening to Detroit say "but we can't possibly do that", where "that" seems to be anything but build bigger cars with worse fuel economy. So why should we believe them this time around?

Especially when foreign manufacturers are doing what they have so much trouble with. If no one could put out a T2B5 diesel w/ better performance and similar mileage I'd be inclined to agree, but there are other companies doing what the ones from Detroit can't seem to figure out, so it doesn't look like this is a technology and/or cost issue.