Convert brake horsepower to horsepower

There are too many variables to convert brake horsepoer to horsepower with a simple equation, it has to do with power transmission.

the "brake" horsepower is the amount of power at the flywheel (the backside of the engine.) from there the power hits the transmission, from there is hits the driveshaft, and finally the wheels, the ratiOS on all of these effect the power, all of each taking its own little chunk away from it.