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Originally Posted by Shownomercy
I guess it leans out the mix and that coulllddd lower temps, but if its running fine before the EGR its not really needed....
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EGR does not lean out the mix. Lean Air/fuel mix burns extremely hot. I can't explain the science behind why recirculating burned exhast gas back into the combustion lowers temperatures but it does.
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EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. Intermixing the incoming air with recirculated exhaust gas dilutes the mix with inert gas, lowering the adiabatic flame temperature and (in diesel engines) reducing the amount of excess oxygen. The exhaust gas also increases the specific heat capacity of the mix, lowering the peak combustion temperature. Because NOx formation progresses much faster at high temperatures, EGR serves to limit the generation of NOx. NOx is primarily formed when a mix of nitrogen and oxygen is subjected to high temperatures.
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