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

F1 engines have been able to achieve over 50% thermal efficiency by recovering heat with a now deprecated device called the MGU-H. Combined with a turbo charger to recover exhaust energy and kinetic energy via braking with what used to be referred to as the MGU-K, an F1 engine is probaly one of the most efficient engine systems that the world has ever seen.