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EGR equipped engines.
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I appreciate the info. There is always something new to learn.
I know that pollution controls on engines drives some people crazy. What I do like, is the cleaner air that is obvious in the Los Angeles area compared to what it used to be. The smog has been reduced significantly.
When I start my old ’64 car in my garage in Palm Springs, I can’t stay in the garage very long, so many fumes! The new cars are so much cleaner!
Safe travels,
Mark
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I’m sure the air is cleaner in many communities because of the increased air abatement equipment on internal combustion engines. When electric cars and trucks catch on, things will really get better!
Too bad we didn’t move to compressed natural gas (CNG) a long time ago for medium and heavy trucks. Air would have been cleaner, sooner.
What I struggle with intuitively is the apparent fact that some “cleaner” engines have inferior fuel mileage numbers. That just doesn’t make sense to me. Maybe sometime I’ll learn why.
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Lean fuel mixtures causes high cylnder temps, witch allows oxygen and nitrogen
to mix causing NOx emissions.BAD stuff . So they introduce exhaust gas back into
the cylnder,wich is enert,like throwing ashes on a fire,to reduce cylnder temps
hence EGR. Wich in return reduces engine power and produces more particulates
Where the manufactures calibrators find themselves in a complicated balancing act,
with emission laws
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Not said was that to counteract the circulation of exhaust gases through the engine the engine computer simultaneously introduces a greater flow of fuel to counteract the resulting loss of power. To prevent the added fuel from exhausting in the form of black smoke the turbocharger output is increased so there is a corresponding increase in intake air. To increase that air flow the boost pressure is increased to as much as 50 PSI, the compressed air is very hot, and we are provided with the pleasure of dealing with CAC hoses not rated for the increased temps or pressures.
The exhaust gases going through the engine are not a constant so some of the time the engine is performing as a non-EGR engine, but when the EGR cycle is initiated boost pressures jump from a peak of about 30 PSi to the 50 PSI peak.
Diesel engines by their very nature run very lean mixtures and that in part contributes to their economy of operation. A lean mixture may not necessarily increase the heat or pressure of combustion because there are so many factors that influence the internal cylinder pressure and / or ehaust gas temperature which is a good measure of the heat of combustion.
One way to cool the heat of combustion and thus control NOX is to add more air (or less fuel), but in doing that engine performance is adversely impacted.
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They keep making the engines larger to offset the power lost and that takes fuel,I was reading by 2025 the 16L will be the norm for truck and bus engines who knows we may see the 3408-18L make a comeback
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