CO2 injection

[SaabJohan]

Originally Posted by beef_bourito

actually, you might be able to run an engine on just oxygen and say kerosene or diesel. make it a 2 stroke and it injects oxygen and fuel which burn as they're injected and then when the piston reaches the bottom a valve opens for the exhaust. ill have to try it one day.

Engines running on LOX (liquid oxygen) have been tested. The idea is quite simple, you cool some of the exhaust and bypass it to the inlet where it is dilluted with oxygen. Was used on some submarines.

Injecting CO2 is a bad idea though. CO2 is inert, it's the final combustion product. Any injection of CO2 will reduce volumetric efficiency and cut engine power. The detonations might end though.

Water injection also decrease volumetric efficiency; some water is turned into vapor before the inlet valve closes. This amount of steam then displaces air and even though the air might be slightly more dense VE goes down. Fuel injection have the same effect, that's why you can get more power from direct injection than indirect injection. Water can however decrease detonation by reducing combustion temperatures/pressures.