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1. Rayfield (rayfield@poa.st)'s status on Sunday, 17-Sep-2023 11:46:44 JST Rayfield
   Oh man I was doing a bunch of reading on this because I've been tweaking my car for more mpg (successfully, now I'm getting 33.5 on the highway instead of 26).
   
   According to what I was reading cars are tuned to run fairly rich so the catalytic converter can fire off and do its thing. Running too lean will inhibit the cat from working but also reduces some emissions while increasing NOx emissions, to a point. When you start to get really lean NOx goes back down.
   
   Another guy I was talking to told me that Lycoming aircraft engines use a process of leaning the engine to find peak EGT @75% power. Then +100 deg richer EGT for power or -50 deg leaner for best economy. That works out to 18:1 economy and 14.5 power ( @WashedOutGundamPilot Is this accurate? Do you know if this guy was full of shit or not? )
   
   It was making me wonder if there are better ways to cut back on car emissions instead of the federally mandated catalytic converter that requires you to run much richer than necessary and sacrifice how many miles per gallon you get.