I'd have to politely disagree with a few statements of yours.
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Originally Posted by cujet
... Remember, EGR generally does not flow at WOT and/or high power settings. Yet, that high compression functions just fine. EGR simply allows the use of high compression without exceeding oxides of nitrogen emissions.
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This is not completely true. At WOT, engines run in open loop and enrich the air/fuel mixture to function fine. This kills efficiency.
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What's possible with very high compression, very lean burn and moderately advanced timing without EGR is impressive indeed. Experimental air cooled aircraft engines (operated lean of peak EGT, with high compression pistons, 2 plugs per cylinder and timed for optimum efficiency) regularly achieve BSFC numbers well below 0.38 pounds fuel per HP/HR. Some brag about numbers below 0.35, on gasoline! EGR does not help in any way under these conditions.
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These engines are specifically designed to run lean. Engines designed to run EGR could do the same thing. Perhaps not to the extent of lean burn, but it can be used in a similar fashion and without the NOx problems that lean burn causes. I'm not saying all engines do do this (especially older ones), but some definitely do.
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There is much more, but those are the basics. EGR is generally not helpful or harmful in modern engines with regard to fuel economy.
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Sorry, a bunch of published SAE papers would disagree.