Rumors have been swirling of a new smaller-displacement Cummins diesel for the 2010 Dodge Ram 1500. But until now, nobody had any idea exactly what size the new oilburner would be. According to a sticker spotted under the hood of a 2009 Dodge Ram 1500, the new diesel will displace five liters. What we find particularly funny is that the sticker specifies the air-conditioning refrigerant charge for each of the Ram's available engines, but all the engines have the same charge specification, so the sticker doesn't really need to specify engine displacement in the first place. The heavy-duty Ram 2500 and 3500 are currently available (and evidently will continue to be) with a 6.7-liter straight-six Cummins diesel; the new five-liter mill should be for light-duty Rams, to go up against GM's 4.5-liter Duramax diesel, Ford's 4.4-liter diesel, and maybe even a diesel V8 from Toyota. Whether or not Chrysler will be sharing this engine with Nissan as they are with the Hemi remains to be seen. Let the diesel muscle truck wars begin! [PickupTrucks.com]
Ahem, let me try and explain the lack of small diesels once again. Currently, we have in place a set of emission standards that are ever evolving every 2 to 3 years. Within the US, the regulators have determined that Diesel Particulate matter, as well as Nitrous Oxide emissions need to be checked. Our NOx standards are more stringent than either the European, or the Japanese standards, and even stricter in the states of California, New York, Florida, and other left leaning liberal enclaves.
First, to combat Particulate Matter, there has to be a Particulate Filter, attached to the exhaust system. When there is a buildup of soot, there has to be a regenerative phase in which most of the particulate matter is burned (and this is usually done by dumping fuel within the filter, raising temperatures within the filter, and thereby decreasing your fuel mileage). You have to utilize clean diesel fuel with next to no sulfur content so that the catalyst, also embedded within the cannister, won't become useless.
Second, to combat Nitrous Oxide pollution, you have to have a two step process. Step one is to decrease combustion temperatures within the combustion chamber of the engine (NOx is prevalent in high temperature combustion), and step two is performed by the Catalytic Converter. To cool down the combustion temperatures, you can either have fuel pre-injected into each cylinder prior to compression (which has been done, but not enough to meet the newest standards), inject eurea formaldehyde into the combustion chamber prior to compression (what is being proposed for the newer truck engines), or utilizing an Exhaust Gas Recirculating valve, in which exhaust gasses are channeled through an intercooler (like one used for Turbocharged engines) and re-introduced into the combustion chambers.
What this does is decrease the fuel efficiency that is inherent with the Diesel Engine. Yes, it may still get better fuel economy, and they still have a better torque rating than gasoline engines of similar displacement, but they are becoming more complex, with a greater number of items that need to be checked, or that eventually fail. And with clean diesel hovering at around $1 more per gallon than regular unleaded, and he increased cost associated with checking the Diesel Option on the order sheet, payback will be a long time coming.