For thr OP's airplane 46 is good enough is what I wanted to say. Think we are on the same page, just reading different lines. You dont have to dive a plane to do a loop if you are using a lower size engine, just add power a bit earlier so you have the airspeed at the start to finish the loop. Also, you cant do loop after loop (atleast I couldnt, but may be with more throttle management...) thats all

Ameyam