So far we have several of the best tank engines mentioned.
Soviet V-2 diesel - T-34 and many more.
US GM 6046 diesel as used in Sherman M4A2 and M4A2 based M10.
US Ford GAA as used from M4A3 and M4A3 based M10.
UK Meteor - Cromwell, Comet, Centurion.
I would add the German HL120 - Panzer III and IV plus derivatives (Stug III in particular).
Soviet V-2 diesel - T-34 and many more.
US GM 6046 diesel as used in Sherman M4A2 and M4A2 based M10.
US Ford GAA as used from M4A3 and M4A3 based M10.
UK Meteor - Cromwell, Comet, Centurion.
I would add the German HL120 - Panzer III and IV plus derivatives (Stug III in particular).