Urea injection for diesel

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Originally Posted By: artificialist
Mazda avoided using urea injection because they created a diesel with 14:1 compression. That kept peak combustion chamber temperatures down, avoiding the higher temperatures that create NOx.


In theory so far. Mazda has delayed the introduction of their Diesel to North America. I think the problem is certification.
 
Originally Posted By: montr
Originally Posted By: artificialist
Mazda avoided using urea injection because they created a diesel with 14:1 compression. That kept peak combustion chamber temperatures down, avoiding the higher temperatures that create NOx.


In theory so far. Mazda has delayed the introduction of their Diesel to North America. I think the problem is certification.


Yes, I have heard rumors that the engine has bad fuel dilution due to frequent DPF regeneration, and that it takes a while to warm up, which raises cold weather emissions.
 
Originally Posted By: wemay
Chevy advises to fill every 10k mi or so. Out of curiosity, what would happen if you failed to do so?


My vehicle gives a warning of "999 miles until no start". IMO if you can't fill with that mileage you have no business driving.
 
Originally Posted By: TiredTrucker
I would have much rather the Urea/SCR thing would have been done first instead of the EGR [censored]. I don't care for any of this stuff, but having all emissions stuff handled outside the engine is a far better way to do it than making an engine eat it's own feces. As a side note, it has been shone that they can reduce EGR because of the SCR, and this in turn allows the engine to be more efficient and in turn the DPF doesn't have to do regens as frequently. Now, if they could just do away with the EGR, things might be more tolerable.


Urea injection is better in every way compared to the heavy egr thats needed to control nox.
Ok, it has one drawback...you have to fill at a rate of 1-3% but the tanks are generally big so its usually every third tank or so.
The def tech saves you about 3 bucks of diesel for every buck that you buy def fluid for by simply
allowing the engine to run at higher efficency, egr lowers the engines efficency..
 
Originally Posted By: montr
Originally Posted By: artificialist
Mazda avoided using urea injection because they created a diesel with 14:1 compression. That kept peak combustion chamber temperatures down, avoiding the higher temperatures that create NOx.


In theory so far. Mazda has delayed the introduction of their Diesel to North America. I think the problem is certification.


OMG, there is no end to the Skyactiv dynasty is there?
 
Despite my disgust for the politics that brought this about, it will make factory water injection more likely in the future. It also creates new tanks for people that owned the vehicle before the EPA vomitted on it to use for water/methanol kits, referring to Duramaxes in particular.
 
Originally Posted By: artificialist
Yes, I have heard rumors that the engine has bad fuel dilution due to frequent DPF regeneration, and that it takes a while to warm up, which raises cold weather emissions.


The regen thing I get, the warm up??? Other than some higher thermal efficiency, I dont see a substantial difference to warm up a diesel than a ga$$er, because if the same alloys, lube types, etc. are used, and the same power is output, its a matter of mass and heat capacity.

The diesel is more efficient, but the few % dont make a big difference given the quantity of waste heat. The engines are heavier, but that heat capacity difference can be calculated, and if normalized, wouldnt be any longer. Practically speaking it may not be any different.
 
Originally Posted By: JHZR2
Originally Posted By: artificialist
Yes, I have heard rumors that the engine has bad fuel dilution due to frequent DPF regeneration, and that it takes a while to warm up, which raises cold weather emissions.


The regen thing I get, the warm up??? Other than some higher thermal efficiency, I dont see a substantial difference to warm up a diesel than a ga$$er, because if the same alloys, lube types, etc. are used, and the same power is output, its a matter of mass and heat capacity.

The diesel is more efficient, but the few % dont make a big difference given the quantity of waste heat. The engines are heavier, but that heat capacity difference can be calculated, and if normalized, wouldnt be any longer. Practically speaking it may not be any different.


Diesels are infact so effective at idle that they generally cant keep hot..
 
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Why not kick all of this EPA garbage to the curb and go back to reliable, simple diesels?

Oh, wait, then Al Gore wouldn't be a multi billionaire ...
 
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Originally Posted By: Miller88
Why not kick all of this EPA garbage to the curb and go back to reliable, simple diesels?

Oh, wait, then Al Gore wouldn't be a multi billionaire ...


Maybe we should all just go back to walking everywhere. It was much simpler and more reliable.

The concepts around EGR and SCR are sound.
 
Originally Posted By: Miller88
Why not kick all of this EPA garbage to the curb and go back to reliable, simple diesels?

Oh, wait, then Al Gore wouldn't be a multi billionaire ...


Because then you'd have a diesel generating 100hp and 300tq out of 8 liters of combustion.

The reasons diesel's run so well and make so much power is the multiple computer controlled injection events. Mechanical simply cannot do that. It may be more reliable but that is the only benefit.

Why not ditch FI and go back to carbs? Simpler right?
 
Originally Posted By: BMWTurboDzl

Maybe we should all just go back to walking everywhere. It was much simpler and more reliable.

The concepts around EGR and SCR are sound.


Yes, but IMHO, EGR does not belong on a diesel engine. Period.



Originally Posted By: Thermo1223

Because then you'd have a diesel generating 100hp and 300tq out of 8 liters of combustion.

The reasons diesel's run so well and make so much power is the multiple computer controlled injection events. Mechanical simply cannot do that. It may be more reliable but that is the only benefit.

Why not ditch FI and go back to carbs? Simpler right?


All was fine and well in the world of diesel power until 2007 EPA regulations. Then it took a turn for the worse with 2010 EPA standards. Engines before these emissions regulations were able to achieve decent output; heck, most pre-07 engines could run on recycled vegetable oil just fine, similar to Rudolf Diesel's original engines that were not at all picky about fuel. And look what happened to Caterpillar post-2010.
 
We went through that same complaint with gassers with the first big round of environmental regulations. It worked out with gassers. It'll work out with diesels. I don't envy those who have to suffer it out now, but things will improve down the road.
 
Originally Posted By: Garak
We went through that same complaint with gassers with the first big round of environmental regulations. It worked out with gassers. It'll work out with diesels. I don't envy those who have to suffer it out now, but things will improve down the road.


Sounds virtually verbatim to the arguing about catalytic converters in the early 70's to me...
 
Originally Posted By: AP9
Originally Posted By: BMWTurboDzl

Maybe we should all just go back to walking everywhere. It was much simpler and more reliable.

The concepts around EGR and SCR are sound.


Yes, but IMHO, EGR does not belong on a diesel engine. Period.



Originally Posted By: Thermo1223

Because then you'd have a diesel generating 100hp and 300tq out of 8 liters of combustion.

The reasons diesel's run so well and make so much power is the multiple computer controlled injection events. Mechanical simply cannot do that. It may be more reliable but that is the only benefit.

Why not ditch FI and go back to carbs? Simpler right?


All was fine and well in the world of diesel power until 2007 EPA regulations. Then it took a turn for the worse with 2010 EPA standards. Engines before these emissions regulations were able to achieve decent output; heck, most pre-07 engines could run on recycled vegetable oil just fine, similar to Rudolf Diesel's original engines that were not at all picky about fuel. And look what happened to Caterpillar post-2010.


No modern diesel will ever be able to run on WVO, just because you can does not mean you should. Nothing before the mid 80's should ever touch the stuff, it is poison. Rudolf's ran on peanut oil, virgin peanut oil. You want power and fun, you need a quality controlled fuel WVO, VO, Bio-D are not those fuels. It all comes back to straight D2 ULSD.

You want them to still be around you need emission controls otherwise you can also kiss them goodbye.

The industry on the whole is forcing everyone running D2 to step up. I am sure the rail industry is moaning in the same fashion.
 
Originally Posted By: JHZR2
Originally Posted By: artificialist
Yes, I have heard rumors that the engine has bad fuel dilution due to frequent DPF regeneration, and that it takes a while to warm up, which raises cold weather emissions.


The regen thing I get, the warm up??? Other than some higher thermal efficiency, I dont see a substantial difference to warm up a diesel than a ga$$er, because if the same alloys, lube types, etc. are used, and the same power is output, its a matter of mass and heat capacity.

The diesel is more efficient, but the few % dont make a big difference given the quantity of waste heat. The engines are heavier, but that heat capacity difference can be calculated, and if normalized, wouldnt be any longer. Practically speaking it may not be any different.


The big factors affecting diesel engine warmup time is very lean air-fuel ratios that they run at idle, and the fact that they run unthrottled. Air-fuel ratios of a diesel at idle can run 80:1. This means very low in-cylinder temperature, so not much heat is available to transfer into the water jackets. Idling during a winter day, my truck does not make enough heat to keep the thermostat open, and it takes about 20 minutes to get any useful heat out of the heater. There is a downside to high thermal efficiency, depending on how you want to look at it.
 
Originally Posted By: SteveSRT8
Sounds virtually verbatim to the arguing about catalytic converters in the early 70's to me...

And unleaded fuel, and every other change to emissions rules we saw with gassers, too.
wink.gif
 
Hopefully . . . .

It's just kind of scary when you see major players like Caterpillar giving up and leaving the industry completely, and others like Navistar taking quite the beating.

Don't get me wrong, I'm sure they're just (relatively) temporary hiccups, but look how many people seem to be souring on diesels because of these emissions issues.
 
Well, it is unfortunate, and diesel is already behind the 8 ball in a lot of ways. It's not an easy situation for everyone involved. If we want to see more diesel engines, their emissions controls are going to have to get more modern and reliable. If we want their emissions systems to get more modern and reliable, we're going to see some teething problems.
 
Originally Posted By: A_Harman
The big factors affecting diesel engine warmup time is very lean air-fuel ratios that they run at idle, and the fact that they run unthrottled. Air-fuel ratios of a diesel at idle can run 80:1. This means very low in-cylinder temperature, so not much heat is available to transfer into the water jackets. Idling during a winter day, my truck does not make enough heat to keep the thermostat open, and it takes about 20 minutes to get any useful heat out of the heater. There is a downside to high thermal efficiency, depending on how you want to look at it.


This is precisely why we do not use them in our business. Our upfitter has a diesel version that they export to third world countries but it requires a huge heater and all the complex controls to protect it due to the fact that a diesel simply cannot produce the huge amounts of heat we can easily get from a gasser...
 
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