Anybody Alive???

This diesel section sure died off quick. O well I suppose it is a Prius forum.

But there is big news ahead 1/1/11 Thats 4 ones and 4 ones that many mfgs are saying omg too. What does it mean??? Tier 4 emissions for off road engines from 150-750hp. These emissions are nearly as strict as the emissions for 2010 on road engines.

So how are all of the MFGs meeting this?? Well most of the smart ones are using SCR and the dumb ones are using complex EGR systems, whats they difference? Ill explain because im bored. But in all reality i posted this on a diesel site a few days ago so Im not bored at the moment.

Enjoy, im starting to miss this site.

$7.43 per gallon is also a very high price. You wont buy it for $2.50 a gallon unless you buy a semi tanker load, but you can buy it for $3-5 all day long. I buy mine for $4 per gallon right now. Our tractor uses about a gallon every 10 hours. I get it from NAPA, Peak Blue DEF. Its the best price Ive found after looking around and it comes with a nice handy nozzle.

Places to buy DEF include nearly every auto parts store, light duty diesel ford and gm dealers, mercedes dealers, agco/massey/fendt/challenger/case ih/new holland tractor dealerships, truck stops, and every single heavy truck dealership.

Its becoming more and more common and pumps are being put in at many larger truck stops.

It is important to only buy what you need as DEF has a short shelf life of 1-2 years depending on how it is stored.

Its also important to note that it is corrosive so dont spill it on your paint, metal surfaces and especially be careful around electronics.

It is an irritant to so if you get it on your skin rinse it off.


Now there is big dispute over the price, people say "I can go buy fertilizer grade 32% UAN for $1-1.5 per gallon,why are they charging $3-12 per gallon for DEF?" Well my freinds that is because they are hardly the same UAN (Urea Ammonium Nitrate) is only about 16% pure urea the rest is ammonium nitrate to make up the 32% nitrogen, then the rest is water. DEF is 32.5% Pure Urea and the other 67.5% is Ultrapure Water. When you look at the facts, and the concentrations and quality standards of the two, you realize that DEF is priced fairly within the Urea Market.


Then there is the big dispute that prices for DEF are going to soar through the roof because nearly all on-road diesels and most off-road diesels(150hp-750hp) will be using SCR systems and needing DEF.

I dont forsee the automotive demand for Urea causing prices to go up that much, over 90% of Urea goes straight to agriculture. Automotive usage is very low.

Furthermore, DEF price is directly related to natural gas prices since it is made from ammonia and CO2 which is mostly made from Natural Gas these days.

I dont see the price of DEF drastically going up because more people will be using it, if anything I see the government maybe getting involve to regulate the price of it somewhat seeing as how it is required for most diesel vehicles to run, just like fuel.



And of course at the end of all of this you can always drive a cummins. But now lets compare SCR systems to EGR systems.

1st the basic principles, Combustion temperature is a big influence on the production of NOX gases. Hotter combustion means more NOX, cooler means less, in theory.

EGR systems such as those used by cummins and John Deere rely on the engine itself to do all of the emissions scrubbing for NOX mostly by recirculating very large amounts of cooled EGR gases and then use the particulate filter to trap particles.

SCR systems rely on external scrubbing for NOX and a particulate filter to trap the particles.

So lets look at how EGR type engines try to reduce NOX. They want to reduce the combustion temperature and try to reburn some of the exhaust at the same time. To do this they lower compression ratios and add large Cooled EGR systems to the engine.

Now how do the SCR systems do it? Simple, they just inject the DEF, let it react in its catalyst and all is good.

So lets look at the pros and the cons of both systems.

First the physical parts. Its kind of a draw in this section between the two.

EGR systems are large and take up a lot of space in the engine compartment not to mention all of the valves and such.

SCR systems leave plenty of room in the engine bay, however you do have to have a DEF tank and the catalyst which take up some extra space and add some weight.

Now lets look at the cost of parts, everybody know EGR system components are pricey, but so are SCR system components. Case in point, I just replaced the DEF sensor in our new tractor, its a $1400 sensor. I would call this section a draw between the two systems also.


Now lets get to Fuel efficiency, the area where SCR walks all over EGR systems.

EGR type engines have to tune the engine for emissions before worrying too much about power and efficiency.

SCR type engines tune for power and efficiency and let the aftertreatment systems take care of the rest.

Case in point, 397hp Duramax and 400hp Powerstroke are both getting better mileage than the 350hp Cummins.

Next lets look at additional costs over time. Many people bash SCR systems because you have to add DEF. Well check you service book, on EGR systems your changing the oil 1.5-3 times more often. Thats a lot of money. Not to mention the premature wear that has on the engine. Go pull the dipstick on an SCR engine, the oil is actually clean, EGR engines not so much, its nasty.

So operating costs of an SCR system generally are lower because while you have to buy DEF, you dont have to buy as much fuel, oil and oil filters.


Lets also look at that little guy called the DPF the gremlin everybody hates.

EGR type engines pump tons of exhaust back into the cylinders and have low compression ratios, thus providing cooler combustions temperatures. Do you think diesel likes to burn hot or cold? Ding ding ding, hot. Weve known for years, hotter combustion, more complete burn. More complete burn means less particultes.

So generally speaking, SCR systems will require fewer regenerations for the DPF which reduces fuel usage even further and also reduces downtime in the shop due to plugged DPFs that need to be removed and cleansed.


Lets compare this to something other than actual engines.

Lets say your a marathon runner, and your running in California. And since CA is literally nuts they have no imposed a restriction on emissions from your...exit area. Some genious scientist invented a device to take care of one part of the emissions (compare this to DPF) which everybody wears, then there are two other systems one that uses a chemical to reduce your emissions, and one that requires you to breath in your emissions and reuse them with your lungs doing the filtering and such, which runner would you rather be?? Poor analogy I know but you get my point I think.


Many people also complain about the labor it takes to put in DEF. Oh my gosh you have to drive to the store, buy some and put it in the tank. You do this for your windshield washer fluid too because it keeps your windshield clean right?? Exactly. Or if its still too much work for you, you could think about laying under your truck changing your oil twice as often.



So to summarize everything weve learned here are the pros and cons of the systems.

SCR Cons: You have to get away from the TV and buy some DEF and put it in the tank every once and awhile.

SCR pros: Better fuel efficiency, fewer oil changes, longer engine life, fewer DPF regens, and less junk in your engine.


I say SCR FTW, but ill let you decide.thanks:

 

Yes thatsa been the general consensus, that they will be constant load like locomotives. Starting and stopping a diesel doesnt work so well.

DPF regens are completely seperated from the engine on some engines (where the engineers are smart IMO). A downstream injector injects fuel to be ignited for DPF regen.

Now on other engines such as the 6.7L cummins the engine injects fuel on the exhaust stroke. Still basically seperate from the engine but harder on it.

When they really need some heat created they will start to restrict the engine to make the exhaust hotter.

DPF regens are a huge PITA as of now, but im hoping sooner or later they can get it figured out.



But I do like your idea of having the regen when braking, and now after typing for a bit I see where you are going with it. Having it regen when slowing down, then pause when accelerating so that the engines performance is not affected by the regen.

 

nothings ever far away in Europe, theyre light years ahead of us

 

What is your reasoning behind that?

 

oops I always forget about people being in different countries.

Old diesels were noisy and polluted a lot. Now they are quiet and Clean (at least across the pond). The New LML Duramax is queiter than its gas engine counterpart, same goes for the new 6.7L Powerstroke, you cant hear them running anymore than a gas engine and under acceleration, the diesels are actually queiter than the gas engines.


As for people who are too lazy to maintain there emissions systems, try doing that on a new diesel with SCR. It wont run and if it does it will be very limited on power. All of them have failsafes so that if the emissions equipment goes bad, the equipment has to be repaired or the person who bought a 400hp diesel will be driving a 100hp diesel until they can fix it.

The new diesels are damn clean, we have one on our farm. The tractors exhaust is very clean but the smell it gives off from burning the urea is interesting.


But I understand all of your points you make. They make sense. I just like to play devils advocate because many people still have the stereotype that diesels are dirty, noisy and slow.

 

Exactly.

But with diesels the emissions treatment comes after the engine itself, so if the engine isnt maintained, the emissions systems will still take out the particles and such. And if the emissions equipment isnt maintained, the engine goes into reduced power limp home mode. Dont know many gas engines that do that.