What makes internal combustion engines accelerate?

Question

So if an internal combustion engine is idling, when we add more gas/air by opening the throttle why does the engine accelerate? Do the explosions in the cylinders increase in velocity? I would have assumed that the explosions occur at the same speed regardless of the amount of fuel/air in the cylinder. So I don’t understand why the engine rpm increases.

thanks

In: Engineering

Answer 1

> I would have assumed that the explosions occur at the same speed regardless of the amount of fuel/air in the cylinder.

You would assume incorrectly. More fuel burning creates greater force from the expanding hot exhaust in the cylinder. That pushes the piston down harder and faster.