Ecoboost question for DP

   #63  

deezler

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Lots of misinformation here about regens.

First, yes, the new diesels do still regen, and yes the DO use diesel fuel to regen.
Second, DEF is used to lower NOx emissions in order to meet emissions regulations. All trucks with DEF us a special DEF injector to inject DEF into the exhaust to mix with the NOx. The chemical reaction breaks down causes the NOx to combine with the NH4 in the DEF to produce water vapor.
Thirdly, DEF itself does not affect regens and in no way is it tied to regens. However, the use of DEF to reduce NOx allows the trucks to run less EGR, thereby running a bit higher combustion temperature, resulting in less soot buildup in the DPF, which in turn requires less regens. More infrequent regens leads to better fuel economy. Make sense?

They may not be 100% correct, but it is a lot closer than some of the other posts. :)

Just going to quote you here to say thanks for the correct (finally) explanation in this thread.

DEF is urea, only meant to lower NOx emissions. DPF (diesel particulate filter) is only there to reduce particulate emissions. It still has to be regen'ed periodically, whether through late in-cylinder fuel injection (after combustion has ended so that the fuel vapor simply flows out the exhaust valve) or with an in-exhaust injector (better solution, IMO).

Back to the ecoboost engine though, people are saying the turbos are parallel. I guess that is the correct terminology, but it's easy to visualize - the engine is a V6, there is one turbo on each bank, fed by 3 cylinders apiece. Except in very rare circumstances, you'll never see a supercharger put on an engine to increase efficiency. The belt-driven load on the engine is a big parasitic loss on the engine. Turbochargers are far more efficient, being driven by waste exhaust heat.

The 3.5L ecoboost runs a maximum of about 10-12 psi boost depending on ambient conditions. The new 2.7L ecoboost runs more boost, and at leaner air-fuel ratios. I know the journalist-observed fuel economy reports haven't been good, but it should do better in the real world vs. the 3.5.
 
 
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