"Surely you must know that it is an inert gas....it's a great way to
put out a fire....not so much for aiding combustion." -
Joe Walsh
Precise observation. Seems argon liquid to gas is endothermic but not as much as NOx. Adding argon gas increases air densities and combustion temperatures and reduces CO, CO2 and NO2 with cooler exhaust temperatures. Seems HO2S sense less exhaust O2 and ECUs / PCMs advance ignition timing. Diesels have been doing this for years using the same throttle risers, injectors and regulators as NOx systems. Plus, it's cheaper.
Seems argon is not a catalyst and, as it is inert, is not consumed and is recoverable in a closed loop system. Not long ago, at an unsanctioned event at an undisclosed location somewhere in Kali, I saw such a closed loop system in a big Ford diesel truck. Didn't know what it was and team was not talking, but the recovery tank, membrane filter (?) and condenser filled half the bed. Truck hauled *ss!
Ranchers and herders 'round here are doing argon welding gas to improve diesel engine performance and save money and annoyance of DEF. They also fabricate superior suspensions from old auto and farm equipment that are amazing.
Yankee ingenuity.
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.483.2235&rep=rep1&type=pdf
There is more info on da webz but I am now spooling over electronic superchargers.