Otto engine
Diesel engine
Stirling engine
Stirling engine - animation with PV-diagram (easy German)
2-stroke (no thermo info though)
staggered cycles for a car
4-stroke (no thermo info though)
lots of engines (no thermo info though)
several visualizations of Stirling cycle (French)
several visualizations of Otto cycle (French) several visualizations of Joule Brayton cycle (French)
Stirling cycle - fairly clear version of demo machine