Found the kraken engine
https://www.twitch.tv/videos/1750501816
Demonstrating KSP2 Kraken Engine using rapier engine and action group to switch to closed cycle mode while engines are on.
instructions:
Assign closed cycle to action group (custom 1)
Assign air breathing to action group (custom 2) (optional)
Assign toggle engine to action group (custom 3)
To fly:
toggle (fire) engine (click the number 3 key)
switch to closed cycle (click the number 1 key)
to turn kraken engine off, toggle engine again (the number 3 key)
Have fun!
