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Old 10-22-2014, 02:04 PM   #11
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The basic issue is that a diesel produces a lot of NOx. EGR helps control the production of it in the engine, but the amount is still more than what a 3-way catalytic convert can handle at times.

Most, if not all, the diesel cars for sale in the US use SCR with the DEF to control NOx. The urea reacts with the NOx to break it down to nitrogen faster than a catalytic convertor can on its own. The fluid is a tiny expense in the operating costs, and it allows fuel economy numbers near where diesels were before ULSD and tighter emission regulations. Many of these equipped diesels are as clean as or cleaner than their gasoline stable mates.

Those not using the fluid for emissions use a NOx trap. A zeolite captures NOx when its produced in high amounts, and slowly releases it during low producing times when the catalytic convertor can handle. NOx traps need to be regenerated like a DPF though. So overall fuel economy suffers.

Some vehicles may use both to get cleaner ratings for the upcoming Tier III emission standards.

As to why we don't have the smaller diesels and gasoline ones. First, the automotive press considers anything that does 0 to 60 mph in greater than 10 seconds unbearably slow. Many in the public will echo that even though it isn't a factor for their daily drive. Then there is some that still don't think a smaller engine has the longevity of a bigger one. Big vehicles require big engines was the thinking. That attitude is quickly fading, but the turbos on the smallest gas engines aren't seen as completely trustworthy yet.

We also get a more limited choice of engines than you do in Europe. We are lucky to get two to your 3 or 4 choices. Since fuel is still relatively cheap, performance is a bigger draw than fuel economy. So VW and Chevy give us their 2L diesel instead of the smaller one. Then many of the recently introduced diesel cars are luxury brands. So fuel efficiency is an even smaller concern.

The CAFE numbers for fleet economy are the unadjusted numbers from the tests. Many of the small, fuel efficient models might already meat it. The Prius is 70+mpg under it. I think we'll start seeing more diesels in trucks and the larger SUV, crossovers, and perhaps minivans. But not as many as turbo charged, DI gasolines.
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Old 10-22-2014, 03:25 PM   #12
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Interesting info, thank you. It seems one of the biggest tasks in the US is changing people's attitudes. No disrespect, but many Americans come across as quite stubborn, not refering to your good self, and a lot still think diesels are slow, polluting, heavy, expensive to run etc etc. Another example is the oil changes where most Americans still think its normal to use a decades worth of oil in a year.

I think if diesels were to be sold in great numbers in the US, then it would be the larger more powerful ones with 200 - 300 HP that would prove more popular. Modest Europeans buy mostly small diesels as it suits thier needs, and they tend not to attach thier ego's to thier cars like a lot of Americans do. If you do your homework though, there are plenty of diesels that do 0-60 in less than 10 seconds, you've probably heard me quote the 3.0 litre BMW engine with over 300 HP which does 0-60 in 4.8 seconds, not bad for a large heavy family sedan, I can't imagine a similar sized gas engine being much quicker without killing the economy. I think here in Europe, diesels were regarded as "faster" around 2003 when compared to thier gas powered rivals, but like i've said before, the US always laggs in automotive technology marketing, but its slowly catching on.
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Old 10-23-2014, 02:13 PM   #13
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One factor that Americans remember (negatively) was GM's attempt to market diesels on the cheap many years ago using a gasoline block and components which did not provide the durability needed for high compression self ignition. Those mechanical problems coupled with our high sulfur "dirty fuel" turned most drivers off on diesels. For years, the only diesel affordable to the masses were VW TDi's. Again, not appealable to the masses, particularly with only 90 hp (horsepower sells in the USA). Eventually, drivers started to learn that torque is the kick in the pants, not horsepower, and since we have learned the benefits of cleaning up the sulfur in our fuels, diesels are gaining acceptance. We still have a long way to go to catch up with the Europeans, but acceptance is slowly gaining ground, with no stink, no smoke, no marbles in the can to poo poo. Maybe someday (sigh).
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Old 10-23-2014, 03:47 PM   #14
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The first phase-in of low sulfur diesel cost a lot of people a good bit of money. The side effect of low sulfur was also lowered aromatics, and an awful lot of O-rings dried out and started leaking. That called for replacing O-rings in fuel pumps of all makes - Bosch, Roosa, Nippon Densu, and others.

For what it might be worth, my '84 LeSharo 2.0 Renault turbo diesel required oil changes every 3750 miles. It also said, were the unit to be operated in Mexico where the fuel had even more sulfur, the oil change interval became 1000 miles. This leads me to believe the much-touted long oil change intervals are more closely related to cleaner fuel than to better engines.
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Old 10-23-2014, 06:59 PM   #15
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Originally Posted by Charon View Post
The first phase-in of low sulfur diesel cost a lot of people a good bit of money. The side effect of low sulfur was also lowered aromatics, and an awful lot of O-rings dried out and started leaking. That called for replacing O-rings in fuel pumps of all makes - Bosch, Roosa, Nippon Densu, and others.

For what it might be worth, my '84 LeSharo 2.0 Renault turbo diesel required oil changes every 3750 miles. It also said, were the unit to be operated in Mexico where the fuel had even more sulfur, the oil change interval became 1000 miles. This leads me to believe the much-touted long oil change intervals are more closely related to cleaner fuel than to better engines.
It's because our fuel is cheap. European diesel adds the aromatics and lubricants removed with the sulfur back in.

We'll be going to ultra low sulfur gasoline in 2017. Wonder if we'll see such negative effects then.
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Old 01-05-2015, 02:21 PM   #16
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...
The vehicle will give plenty of warnings to it running low on DEF. Even if it runs out, it won't simply die and strand you. It will keep running until the engine shuts off. Next start up will be in a limp mode with a top speed of 25 to 35mph. You won't get stranded in a desert. ...
I'm new to Diesels so grain of salt:

FWIW, limp home mode on a Dodge Ram is limiting 5mph after it goes totally empty AND you try to start it.... i.e. you can drive at top speed "forever" as long as you do not shut off. But, it also begins to annoy/tell you that you need to add DEF tank 500 miles before that.

I've yet to see it (and haven't looked that hard), but I understand that many truck stops offer DEF in bulk (I've seen billboard for QT stations that do that), meaning presumably you can top-0ff at a pump.

Nonetheless, you can find DEF at most any auto-parts store, wal-mart or tractor supply company store. If it makes you feel better, spend $8 - $13 for a 2.5gal jug and take it along (or add to your DEF tank before leaving on your trip). It truly WOULD suck to get stuck in the desert in "limp-home mode" due to DEF low condition (I've been in fuel-low condition in NV desert on an ElectroGlide and worrying sucks.)

To the poster who mentioned stubborn Americans... it's not so much stubborn as "rugged individualism": herding us is like herding kitty-cats with air-horns. We (well, at least I, and I suspect many others here) don't like being told what to do. DEF costs about half a penny US per gallon. No big deal. BUT, having your computer (by mandate in Washington D.C.) limit your vehicle to 5MPH (or even 35MPH) because it might puff out too much >cough-cough< really chaps my hide! I mean I get it, and would gladly comply if ASKED, but being told/forced stirs a natural resistance, "on principal".
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Old 01-14-2015, 09:03 PM   #17
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I have operated the newer water trucks on construction sites. small ford f750 2 axle 2,000.gal and 3 axle kenworth 4,000.gal, and when the truck DEF unit decides to S**T on you, it will not move. It seems that the DEF unit operates ""best"" on Highway application trucks that see 55.mph or more most of the day. High speed and High exhaust temperatures. But on a construction site, 5.mph is as good as you get driving on dirt and controlling dust working with other heavy equipment. The DEF unit uses High Exhaust Heat to burn off the crap the DEF adds to the exhaust, and in a business of low speeds and low RPM, it tends to plug it up with DEF and cause the truck to quit. We have had Empire Equipment out to our site 3 times in one month for there 2 trucks that just quit on us. it took them 2 hours of the ""ReGen"" for the truck to operate (mostly) right again. These 2 trucks were the most gutless and sluggish trucks I (or the other driver) have ever operated. The old 1987 1988 ford 9000 company owned trucks were brought in because of the cost of down time from mid morning till late after noon, and the cost of the mechanic to drive out to our remote location to "fix" these problem trucks, as well as other down times for other equipment problems. Newer may not always be (or ever be) "better" (the A/C never did work on them new trucks, and that is a big deal when you work where it is 115+ in summer) but the old trucks keep on working and providing the comfort of COLD A/C.
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