How does an engine turn fuel into motion?

An internal combustion engine turns fuel into motion through a controlled sequence where chemistry becomes physical force ^[1]. Think of the cylinder as a miniature cannon shell and the piston as a sliding metallic plug trapped inside it ^[2]. When a spark ignites an enclosed mix of air and fuel, the resulting combustion creates a sudden surge of expanding high-pressure gases ^[3].

This controlled explosion acts like a heavy shove against the top of the piston, forcing it rapidly downward in a linear stroke ^[4][5]. Because the piston is linked by a pivoting metal rod to an offset arm on the crankshaft, this linear downward thrust is translated into rotational torque, spinning the crankshaft around its axis ^[6][7][8]. That continuous rotation is ultimately routed through the vehicle's transmission and gears to turn the wheels and create usable motion ^[9].

Would you also like to know how the four strokes of the engine cycle work together?