Good Idea/Bad Idea

[Splatpope]

It's a real scientific principle, pal.

No, it's hot stuff + cold stuff = magic energy, the actual joule cycle machine inside the engine, which would be way more fun to work out than simply flushing hellfire into pipes, is not available and that makes the engineer that I am in real life very sad

Understand that we're not working with a machine but solely with it's heat sources

That gets us to the point where only the temperature difference between the hot loop and the cold loop should matter and there are obviously other things involved (pressure in the loops ? It should not have any importance inside the engine itself)