E46Fanatic
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Yes probably true, more fuel is needed to control NOx emissions on typical DI engines during their stratified lean burn process. But HPI engines _can_ run on non sulphur free fuels, and BMW has to tweak the engine/map to allow for sufficient thermodynamic efficiency. Hence we have the 335i, 740i etc here locally.
VW/Audi has a solution for their DI engines and non sulphur free fuels...
"One of the previous problems engineers have had with stratified-charge technology has been high nitrous oxide (NOx) emissions, due to the excess of air. In Audi's FSI engine, this has been controlled by a new exhaust gas recirculation system, and total NOx emissions are cut by up to 70%. Up to 35% of the total exhaust gas is diverted back up into the combustion chamber - effectively sent back to be ignited again. This system works in conjunction with twin catalytic converters, containing NOx sensors, which convert the oxides back into harmless nitrogen gas, as present in the atmosphere naturally."
BMW can at least follow their footsteps and introduce mass market DI engine lineups to us consumers... I sometimes wish BMW leads and VW/Audi follows, but lately this is not the case..
VW/Audi has a solution for their DI engines and non sulphur free fuels...
"One of the previous problems engineers have had with stratified-charge technology has been high nitrous oxide (NOx) emissions, due to the excess of air. In Audi's FSI engine, this has been controlled by a new exhaust gas recirculation system, and total NOx emissions are cut by up to 70%. Up to 35% of the total exhaust gas is diverted back up into the combustion chamber - effectively sent back to be ignited again. This system works in conjunction with twin catalytic converters, containing NOx sensors, which convert the oxides back into harmless nitrogen gas, as present in the atmosphere naturally."
BMW can at least follow their footsteps and introduce mass market DI engine lineups to us consumers... I sometimes wish BMW leads and VW/Audi follows, but lately this is not the case..