Turbocharger Thrust

[Zipper730]

Does anybody have a diagram of the XF-12's nacelle?

 

[Joe Broady]

From what I remember, 1 lbf = 1hp at 350-375 mph, and the increase/decrease from that is proportional to the increase in speed.

The speed where one pound of thrust equals one horsepower is 375 mph. That stems from the definition of the horsepower: 33,000 foot pounds of work per minute. That is, one pound of force at 33,000 feet per minute equals one horsepower. When you convert 33,000 fpm to mph (33,000 / 5280 * 60), the result is exactly 375 mph.

You are correct that a pound of thrust at some other speed gives more or less horsepower, proportional to speed.

 

[Zipper730]

This might be of interest to some people.
Design of nozzles for the individual cylinder exhaust jet propulsion system

Agreed