Exactly how does the piston and crank produce power without the expanding fuel/air mix? They don't.
how does the expanding air/fuel mixture produce power without them?
1) spark plug ignites the air/fuel mixture.
2) this creates a flame front in a controlled burn.
3) this forces the piston down, creating your kinetic energy.
4) the crankshaft converts this "flat" kinetic energy into "rotational" energy(torque)
the crank, and piston in essence DO create the torque. without them, the air/fuel mixture would simply "flash" and do nothing. there would be nothing to create the torque.
so now.......what makes your car move?