In the large aircraft I work with, we have a system called the Onboard Inert Gas Generating System or OBIGGS, (Aviation is full of abbreviations). It seperates nitrogen from the surrounding air by the use of micromembranes, compresses it into storage tanks and dissipates it into the outage of the fuel tanks to inert the gasses in the tanks. If some of you engineer types could come up with a compact version of this to seperate the NOx from the exhaust gasses to pump back into the intake system, we could be onto something here.

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83 W123 240D
76 300D, "Lil Yellow Car"
1978 Cessna 172N 180 HP Mod

"If life ain't fun, I'm not interested"

The important things are those that you learn after you know it all.
Chip Foose

Build a better mousetrap and you will REALLY infuriate corporate america.