Looking at P40 Speed Performance Numbers...

[ElAurens]

Here are the engine types and ratings for various Hawk 87s...

P-40D, E and E-1: V-1710-39/F3R
T.O.: 1150bhp @ 3000rpm @ Sea Level. Manifold Pressure 46.2" HG.
Military: 1150bhp @ 3000rpm @ 12000ft.
Normal: 1000BHP @ 2600rpm @ 11000ft. Manifold Pressure 38.7" HG.

P40F: V-1650-1 Merlin
T.O.: 1300bhp @ 3000rpm @ Sea Level. Manifold Pressure 54.3" HG.
Military: 1240bhp @ 3000rpm @11800ft. Manifold Pressure 48.2" HG.
Normal: 1080bhp @ 2650rpm @ 9500ft. Manifold Pressure 44.2" HG.

P-40K: V-1710-73/F4R
T.O.: 1325 @ 3000rpm @ Sea Level No MP given.
War Emerg. : 1550bhp @ 3000rpm @ Sea Level(Rammed)
Military: 1150bhp @ 3000rpm @ 11800ft.
Normal: 1000 @ 2600rpm @ 11000ft.

P-40M/N-1: V-1710-81/F20R
P-40N20/-35: V-1710-99/F26R
P-40N-40: V-1710-115/F312R
T.O.: 1200 @ 3000rpm @ Sea Level
W.E.: 1360 @ 3000rpm @ Sea Level(Rammed)
Military: 1125 @ 3000rpm @ 14600~15500ft.
Normal: 1000 @ 2600rpm @ 13800~14000ft.

[secretone]

I am no expert and I ask the following question in the spirit of learning. Did the Merlin in the P-40F have a two stage compressor like in the Mustang and Spitfire? I understand that the Allisons did not... If so, then I do not see why it was not the fastest of the p-40 series.

[IceFire]

What does the "Rammed" indication mean at Sea Level?

Interesting that the K seems to have the greatest power? What's the story there?

[ElAurens]

Originally Posted by IceFire

What does the "Rammed" indication mean at Sea Level?

Interesting that the K seems to have the greatest power? What's the story there?

They are taking into account the effect of the air being rammed into the carb intake because of aircraft speed, unlike when an engine is running on the ground attached to a dynamometer.

[secretone]

So there was not a huge increase in performance in the F model because the blower was only single stage. Apparently Packard was not yet producing the 2 stage version of the motor at the time the F model was in production.

Here is a discussion thread for anyone who wants to explore this further:

http://www.ww2aircraft.net/forum/avi...40s-30910.html

[ElAurens]

Interesting discussion there, thanks for the link.

[ElAurens]

Originally Posted by secretone

I am no expert and I ask the following question in the spirit of learning. Did the Merlin in the P-40F have a two stage compressor like in the Mustang and Spitfire? I understand that the Allisons did not... If so, then I do not see why it was not the fastest of the p-40 series.

It was a two speed supercharger, not a two stage one, unlike the P 51, Spitfire, etc... that had 2 speed, 2 stage units. The F was the fastest above 15000ft.