Engine power question???

I own a Cessna 150 with a 150 HP engine installed (0-320- E2D)

The STC states the static RPM is not to be over 2250 RPM.

My airplane meets the Static RPM Requirement.

My question is am I getting the full 150 HP on takeoff??? turning
2250 RPM

When rolling down the Runway the Tach reads about 2250 RPM

During stable Cruise the engine spins up to 2600 RPM ++ full
throttle : no problem

It seem's to me that the engine should turn much faster like 2700
RPM or so for 150 HP??? on takeoff Just like a Cessna 172!

Turning 2250 RPM seems like I am not getting the full rated engine
HP??? perhaps 125 HP or so???????

What sets the engine RPM?? is it the diameter of the prop?? or is
the Throttle travel
limited???

Why would the STC limit the Static Engine RPM to 2250 RPM???

is it because the Tip of the props may exceed speed of
sound ????

The STC states the Prop is a Mccauley 1C172/TM not over 74 inches
not under 72.5 inches.


Thanks for input