Re: 08 dodge 2500 diesel fuel mpg $
There are a few points that need to be understood on 2008 emission (USA) compliant diesels.
1. All of these engines use EGR (exhaust gas recirculation) to help bring down NOx. NOx is a function of combustion temperature. The higher the temp., the more NOx. EGR systems cool the combustion process. Hopwever, EGR systems rob a lot of useable power from the engine. Some systems recirculate as much as 25% of the exhaust gases. The only way to get that lost power/efficiency back is by increasing displacement of the engine.
2. 2008 compliant engines have a DPF (diesel particulate filter). Just as it sounds, this filter cleans out "soot" in the exhaust.
3. DPF's will clog-eventually. Idling greatly increases the load on the filter.
Turn it OFF! These new diesels are
different and idling is not recommended or needed.
4. DPF systems have a built in "regeneration" cycle. This process is needed to clean out the filter and keep the exhaust system free of excess backpressure.
5. Regeneration occurs by the engine computer sensing an exhaust restriction and signaling the injectors (or single injector) to dump raw fuel into the exhaust stream. This allows the DOC (Diesel Oxidation Catalyst) to heat up and generate enough heat for the DPF to "light off" and burn out the soot.
This is where fuel economy suffers. There is no driving energy derived from that fuel being dumped into the exhaust.
Again, excessive idling just makes this situation worse. This is also where one might find an unwanted issue-engine oil dilution
With all that said, 2010 compliant engines will use the same system with the addition of UREA. Urea is basically anhydrous ammonia (32%) and dionized water (68%). Urea will turn exhaust gases into NO2 and water.
Urea will be sold in various sized containers and dispensed near diesel fuel pumps. At least that is the plan.
Urea usage is
expected to be about 1% of fuel usage.
Urea prices are expected to be about $4.00/gal.
Urea injected systems will increase fuel economy dramatically. The regeneration process (DPF) will be cut by as much as 90%.
In addition, 2008 and up compliant diesel engines
MUST use CJ-4 rated engine oil. Anything less will have catastrophic (read expensive) consequences, the first being a permanently clogged DPF.
A couple more tips.
1. Other than California, diesel fuel
cetane ratings are NOT mandated. Cetane is a functon of the diesel fuels ability to burn. The higher the cetane rating, the better the fuel and the better (cleaner) it will burn.
2. I see cetane ratings as low as 35, in many areas. Most of todays diesels need at least 45 cetane to run properly.
Low cetane fuels lead to EGR coking. It is the number one cause of this.
3. I highly recommend a
cetane booster be added to diesel fuel (unless you absolutely know your fuels rating). Adding the booster can increase MPG by as much as 2 MPG. Most cetane boosters are about $6.00 for enough to treat 35 gallons.
4. These new diesels are very maintenance intensive. However, if one follows the makers maintenance recommedations to the letter, they will perform great.
There is a huge "learning curve" going on in the diesel market right now. Operators need to be educated on the proper operation and maintenance of this new generation of diesels. A good rule of thumb is to change engine oil and filters every 200 hours of operation. Most of todays diesel trucks have an hour meter incorporated into the odometer.
Your absolute BEST source of information is your
owners manual.
There, I said it, I referenced the least read book in the history of the world.
