I think you miss couple of points
1,at sea level the Griffon only put out about 1800hp,and the DB605DB also put out 1800hp at sea level,and the 109 is smaller and also 505kg lighter,and yet the K-4 is only 6mph faster and is completely out climbed by the mkXIV,
Doubtful - UNLESS the Induced Drag of the 109K was MUCH higher than the MkXIV at climbing velocities. At the same rated HP, the Thrust should be reasonably close if the propeller efficiency is nearly the same. The equations for Rate of Climb is
=Excess Power/W which in turn, for a given Velocity = (T*V - D*V)/W.
As for introducing Wing or Lift Loading into the equation ---------> in climb each aircraft will have Relative reduced Total Drag at the climbing velocity than for the Total Drag for level flight for that velocity. The Change in Drag for the same relative and respective velocity is due to both form drag increases as well as Induced drag increase.. suspect without proof that the angle of climb is nearly equal. More on this subject below.
2,The Griffon on 21lb boost at sea level put out about 2000hp,the DB605DC also put out 2000hp.
the K-4 is the smaller lighter plane and yet is only 8mph faster and still get out climbed
why is the smaller lighter plane with such a better power to weight ratio gets out climbed and has hardy any speed abvantage,were did that P/W abvantage go to
3,the MKXIV on 25lb boost can hit 380mph at sea level,
4,I like to see the test date for the K-14,as I don't think it got any were near that speed without NOS.
So, for each model Spit vs 109, the thrust of the engine plus the Lift of the wing offsets the Weight of each respective airframe and Thrust = Total Drag + W*sin(alpha) and Lift = W*cos(alpha). If we postulate that CDo and Form Drag are about the same (argue the differences later) then Total Drag = Zero Lift Parasite Drag plus Induced Drag.
Induced Drag = (CL)^^2/(Pi*AR*e); CL = Lift/(Q*S) = W*sin(alpha)/(Q*S)
If the Bf 109K Weight = 7450 pounds. Spit XIV Weight = 8400 pounds 109K W= .88 of Spitfire W.
Wing Area S 109 = 172sq ft; Spit Wing Area = 242 Sq Ft.
for 109 ------> CL= 7450*Sin(alpha)/Q*172)
for Spit------> CL= 8400*Sin(alpha)/Q*242) let Sin(alpha)/Q = K
CL109 = K*7450/162 = K*43.3
CLSpit= K*8400/242 = K*34.7
-----------> Ratio of 109 CL to Spit CL = 43.3/34.7= 1.24
-----------> For equal Oswald efficiency and AR the Induced Drag Ratio of the 109 over the Spit is (1.24)^^2 = 55% greater than the Spit. To get to the actual Drag to insert into Total Drag = Parasite Drag + Induced Drag we need all the differences including climb angle and climb speeds to obtain Q= 1/2*(rho*V^^2) and Sin(Alpha), the Real CDo for each.
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To summarize, despite the same thrust engine performance, and despite the 10% less weight, the offset to the much greater wing loading of the Bf 109K in climb seriously impacts its advantages of smaller size and gross weight because of the much higher Induced Drag in climb...
Those same factors are not near as important at high speed in level flight which is why the Bf 109K should be faster than the Spit XIV given same HP at the compared altitude.