eli5: why are ICE engines only able to achieve 20-30% thermal efficiency?

Question

I read that a massive portion of usable energy is wasted and turned to heat instead of being used to turn the crankshaft — would there be like any way of reducing the heat/cooling the engine so you could get 50-70% thermal efficiency?

In: 407

Answer 1

Why do people say “ICE engines”? The “E” stands for “engine”. It’s like saying “ATM machine”, “chai tea” or “naan bread”.