Why is the thermal efficiency of gasoline engines so low at 20%-30%?

After the engine spark plug is ignited, the fuel burns and explodes and begins to do work to the outside world. It will experience losses from incomplete combustion, engine cooling losses, mechanical losses from the up and down movement of the piston, pump gas losses from overcoming intake and exhaust resistance, and exhaust gas emissions from exhaust gases. gas loss. In the end, only a small amount of heat energy is left to push the piston and drive the crankshaft to rotate, becoming an effective output.

Is there really no performance difference between spark plugs? Let's take a look at the history and scientific principles of spark plug development
Of course, the knowledge points of junior high school physics are a bit behind. Toyota's 2NR-FKE1.5L engine, previously known as the world's highest thermal efficiency, has a thermal efficiency of "up to" 38%.