Go back to basics in very simplistic terms
The more fuel /air mixture u can put thru in a given time the more power
So a 100cc engine running at say 2000 rpm produces say 10 hp
A 200cc engine at 2000 rpm produces 20 hp
A 100 cc engine produces 20 hp @ 4000 rpm
Get the picture?
more rpms more volume per minute more fuel mixture...
One can also increase the furl mixture by pumpiing in under presuers for each rpm..this is where superchagers and turbos come in
the faster or stronger it is?
The faster and engine runs the higher the speed of compents move..lets take an example
pistons...higher the rpm the faster the piston has to move at to get from one end of the stoke to the other in a given time...That is it is at a stopped pistion at the bottoms, accerates to huge speeds then suddenly comes to a top and changes direction to go down again!!!!! this loads bearings cranks etc etc
Therefore an engine 200cc engine at 2000 rpm producing 20 hp has far more stress than an engine of 100cc which revs at 4000 rpm to produce/burn the same amount of fuel.
There is a 'curlly ' that gets thrown into this equation
By nature of the engines, internal combustion, electribc motors etc
The smaller the size the more power that can be produced per cc
If a 200cc engine at 2000 rpm produces 20 hp
If you have 200 1cc engines all hooked up together at 2000rpm the hp increases dramatically even producing several 100% more
Remember this is going back to the very basic principle of engines.