Allpar Forums banner
61 - 69 of 69 Posts

·
Vaguely badass...
Joined
·
43,887 Posts
IIRC, what I read was that engine makers were relying on the higher sulfer content to help with some aspect - lubrication, perhaps? - and reducing the sulfer (sulphur? :huh:) content caused more friction - thus reducing economy. Can't recall where I read that at this moment, however - and I could be remembering it completely wrong.
 

·
Registered
2017 Ram 1500 3.6 Crew
Joined
·
6,374 Posts
Low sulfur fuel was required for the latest emission technology to work. That technology did lower the fuel mileage by quite a bit just like when unleaded fuel was required for cars. It will take a couple of more years for the manufactureres to catch up and get the mileage ratings back. The class 8 manufacturers had a hard time keeping up with orders that were to be produced before the required emmission changes and then had to lay off because few wanted the new engines. We have had manufacturers completely redesign the powerplant areas to accomodate the new emmission requirements. One of our track drills had to lengthen the powerplant area 8" and find even more compact hydraulic drive components to keep it that short.
 

·
Administrator
1974 Plymouth Valiant - 2013 Dodge Dart - 2013 Chrysler 300C
Joined
·
37,211 Posts
Ah, gotcha. Thanks for the clarifications.

I do recall the class 8 production increase/decrease, as I recall Daimler Trucks North America seemed to think the boom would not end.

Natural gas does seem to be the truck fuel of the future, at least for short-haul, day-shift work, -- which is an awful lot of fuel per day. Garbage trucks and grocery suppliers ... supermarkets used to get at least one truck per day, usually two trucks, and three on some days, when I was in the business: perishables, standard grocery items, and nonfoods. Plus whatever is brought by companies like cosmetics companies which do their own separate supply! You add up all those trucks, all that city traffic...

Because many fleet buyers want efficiency, as someone else pointed out here, simply having a standardized fuel efficiency rating based on something more than hearsay will probably do more to raise fuel economy than the new standards, and that's fine with me. I like market solutions. I just don't think the market is able to do everything people need... and since Adam Smith said the same thing (look it up in The Wealth of Nations), I think I'm on solid ground.
 

·
Registered
Joined
·
14,855 Posts
Stratuscaster said:
IIRC, what I read was that engine makers were relying on the higher sulfer content to help with some aspect - lubrication, perhaps? - and reducing the sulfer (sulphur? :huh:) content caused more friction - thus reducing economy. Can't recall where I read that at this moment, however - and I could be remembering it completely wrong.
Correct, as always, Strat!

The reduction in sulphur also increased heat significantly, which has been a big problem for truck manufacturers.
 

·
Registered
Joined
·
1,789 Posts
Stratuscaster said:
IIRC, what I read was that engine makers were relying on the higher sulfer content to help with some aspect - lubrication, perhaps? - and reducing the sulfer (sulphur? :huh:) content caused more friction - thus reducing economy. Can't recall where I read that at this moment, however - and I could be remembering it completely wrong.
Sulfur itself is not a lubricant. The problem is the process to remove the sulfur diminishes some of diesel fuel's natural lubricity. Generally this lubrication only matters to the injection system, as even old diesel fuel was still a poor lubricant in general, and could wash oil off the cylinder walls of engines.

The dramatic loss in economy came from the particulate filters and stronger NOx emission standards. Reducing NOx required a lot of EGR use, which seems to hurt diesel engine efficiency much more than it does gasoline engines. That caused the engine to burn more fuel, produce more soot and require more regenerations of the particulate filter. The newer NOx SCR systems (the urea based ones) remove NOx much more efficiently. Less EGR needed, less soot, happier engine and better economy.
 

·
Registered
Joined
·
846 Posts
NOx and PM production are related; a diesel engine calibration that produces low NOx will generally have high PM, and vice versa.

Without NOx aftertreatment the NOx has to be dealt with inside the engine by using EGR and other techniques that tend to decrease combustion temperatures and combustion efficiency, and that tend to increase PM production. Then the PM is eliminated by accumulating it in the DPF and occasionally using more fuel to oxidize the PM. This is what you generally have for 2007-2009 on-highway HD trucks, and many makes of Tier 4-interim off-highway equipment.

With NOx aftertreatment, the engine can be moved more toward the high-NOx/low-PM end of the scale. This means hotter and more efficient combustion, and less use of fuel to regenerate a DPF. For 2010 most HD trucks still kept the DPF, but use it much less, and use a small amount of DEF for SCR aftertreatment. In off-highway, some products (e.g.: >100 HP CNH products with FPT NEF & Cursor engines) use only SCR and have no DPF at all, while others (e.g. Deere's Tier 4 final) will use a DPF/SCR combination like many trucks are using.
 

·
Vaguely badass...
Joined
·
43,887 Posts
Erik Latranyi said:
Correct, as always, Strat!
I wish it could be "as always" - I'm certainly not right all the time, and not as knowledgeable as others on certain subjects - diesels and fuel being one of them.

And thanks to those that ARE knowledgeable about such things are are willing to take some time to explain it to the rest of us.
 

·
Registered
Joined
·
4,262 Posts
Stratuscaster said:
I wish it could be "as always" - I'm certainly not right all the time, and not as knowledgeable as others on certain subjects - diesels and fuel being one of them.

And thanks to those that ARE knowledgeable about such things are are willing to take some time to explain it to the rest of us.
^^^ THIS x 1000

Danno
 

·
Registered
Joined
·
699 Posts
Dr. Z the problem with CNG is that it has to be compressed, the act of compression takes energy from the power grid, and that energy is essentially wasted as the gas uncompresses to be fed into the engine. Using the gas itself to power a stationary engine running a compressor is not much better since you burn the same amount of gas compressing it as winds up in the vehicle.
However the cost and emissions to compress the gas to 3000psi always gets overlooked.
 
61 - 69 of 69 Posts
Top