How much downwards force is exerted onto a car's pistons when the fuel ignites in a combustion engine?

Question

Car engines, I think, are measured by the amount of torque created when the car's piston is pushed down. What I would like to know is how much force is created onto the piston when the fuel mix explodes.

Answer 1

The answer depends on many things not stated in your question:
Compression ratio
Piston diameter
Air / fuel ratio and fuel used
Whether the engine is normally aspirated or turbo or supercharged.
Spark timing.
Surface/ volume ratio of cylinder and coolant temperature

For some general information, do some searches on a concept known as "mean effective pressure". Also see the link below.