Internal combustion engines produce power when a burning mixture of air and fuel expands. These engines also become more efficient as combustion temperature increases, but to develop maximum power, the energy lost as heat should be kept as low as possible.
If engine parts were made out of materials which did not expand, corrode or melt, heat losses via cooling systems could be reduced or even eliminated. But current engines have cylinder heads, guides and valves which do expand, corrode and melt. So today’s engines, which generally run hotter, still need cooling systems. That