180 degree turn with NO E burned???  Please explain the physics and how to... please  

This ticks me off every time and eventually log off  

  After 10 + years you would think that I should have the answer, instead  

 every time.
This usually occurs with a Spitfire or Ki84, but not limited to those airframes.  I see a guy low near his runway heading towards me (I am tracking another target, so am watching out for his head on attempt, because once I pass him he should be no threat)>>>>>>  WRONG..... 

  He is able to spring into the air climb and 180 degree turn and gain on my 6 o'clock from long range shot position.   
 
  How, and what kind of physics supports this??  Maybe I will be around for another 10+ years to exploit such a maneuver if available in any of my favorite aircraft (depending on my sight).