Attention: TDR Forum Junkies 
Riflesmith - What you say about lower BTUs per unit vol in ULSD is of course correct. However, the higher cetane rating will allow the injection timing to be advanced without exceeding emission limits. By increasing combustion efficiency, the difference in total energy vs current high aromatic fuels should more or less be compensated. I agree that with current deisel engines with retarded timing there should be a small drop off in mileage with ULSD. But I haven't noticed this myself when I run California fuel. Maybe that's because I run at a lower altitude when I'm in Cal.
Cooled EGR is going to extract a mileage penalty when it is implemented. That's because the re-burned exhaust gases will lower combustion temp (in order to lower NOx) and thereby reduce the amount of heat (power) produced. I understand that the effect is only supposed to be 2-3% in the ISBe. EGR is only a stop gap solution for diesel emissions. Diesels are inherently low emission engines when run on the right types of fuel. The only problem is that as the combustion efficiency increases, so does the NOx. So the best solution would be to forget about how much NOx is produced during combustion and clean it up in the exhaust system. Once ULSD is universal, new types of catalytic converters that convert NOx can be employed. This would allow the manufactures to go back to designing engines for efficiency rather than emissions considerations.
It is interesting that the MTBR for the ISBe has been reduced to 350,000 miles vs 400,000 for the ISB. I wonder if this is related to the EGR system or the extended recommended oil drain interval (15,000 miles).
Cooled EGR is going to extract a mileage penalty when it is implemented. That's because the re-burned exhaust gases will lower combustion temp (in order to lower NOx) and thereby reduce the amount of heat (power) produced. I understand that the effect is only supposed to be 2-3% in the ISBe. EGR is only a stop gap solution for diesel emissions. Diesels are inherently low emission engines when run on the right types of fuel. The only problem is that as the combustion efficiency increases, so does the NOx. So the best solution would be to forget about how much NOx is produced during combustion and clean it up in the exhaust system. Once ULSD is universal, new types of catalytic converters that convert NOx can be employed. This would allow the manufactures to go back to designing engines for efficiency rather than emissions considerations.
It is interesting that the MTBR for the ISBe has been reduced to 350,000 miles vs 400,000 for the ISB. I wonder if this is related to the EGR system or the extended recommended oil drain interval (15,000 miles).
