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

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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?

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Anonymous 0 Comments

We will never hit 100% efficiency since humans aren’t perfect and nothing we make will ever be. There are ICE engines that are being tried out which might once fully developed get higher efficiencies. They have a design for opposing pistons for the compression and power strokes where two pistons squeeze the mixture and moved apart from each other then the resulting motion from the two camshafts are combined via gears. Another where they use a compression cylinder to precompress the mixture before moving into the combustion cylinder to reach higher compression ratios. But honestly don’t know how efficient either will finally end up at.

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