Quote:
Originally Posted by Frank Lee
Don't call it EGR cuz EGR = Exhaust Gas Recirculation, and if the gas isn't getting out of the cylinder in the first place, it ain't recirculating!!!
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Internal EGR is still called EGR even if the gas isn't getting out of the cylinder in the first place. It ain't recirculating, just keeping the gas in there for the next cycle, but it's still called EGR.
Quote:
Originally Posted by Frank Lee
I get your theory by the way. The fact is neither of us know exactly what is happening in the cylinder.
"...and since the flapper is increasing the amount of exhaust present in the cylinder during warmup I would say it's increasing EGR."
You don't know that.
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Course I don't. Just like I don't know that EGR helps out with emissions in the first place. But based on what I've read EGR helps keep peak combustion temps down and limits NOx formation within certain bounds and increasing back pressure will likely keep more of the exhaust in the cylinder. Maybe if we were to take a given engine, and could measure everything accurately and precisely, we might find that for a given exhaust system restriction the exhaust gases retained are only marginally higher (or NOx reduction was marginally lower), or perhaps even lower over some range due to light scavenging, but I would wager that in general more back pressure tends to lead to more exhaust gas staying in the cylinder.
