Quote:
Originally Posted by drmiller100
interesting.
i did not know you could have higher intake pressures then exhaust pressures. thinking about it, theory says it sure is possible. though.
thank you.
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You're welcome. One thing that's worth mentioning is that most EGR engines cannot have higher intake pressures--otherwise the exhaust wouldn't flow into the intake. That's one of the reasons some recent diesels (including my truck) are fitted with intake throttles. In situations where the intake pressure is too high to get enough EGR flow, the intake throttle is closed down to increase pumping losses. One more way EGR hurts fuel economy on a diesel.
On a
gas engine EGR can actually help the pumping losses because more EGR allows the throttle to be more open (because fuelling is deterined by the oxygen content in a gasser), therefore EGR raises the intake manifold pressure.