Motor Size Comparison

So we can figure out the horse power by finding out the watts of the motor.
Amps x Volts = Watts.       
745.5 Watts equals1 horsepower .

A 05 Modified motor in Sprint Boat Racing can push out
45 or more amps at 7.2Volts
45 x 7.2 = 324 watts
Mounting holes are 25mm, center to center on most 500 series motors.
A 05 modified motor putting out that kind of power would need to be rebuilt often.
 

A 700bb turbo motor in Sprint Boat Racing can push out
45 amps at 14.4 volts
45 x 14.4 = 648 watts
Mounting holes are 29mm, center to center on most 700 series motors.
At this power a 700bb turbo motor will last a couple of hundred runs before needing replacement!
 

Now this is not to say that 05 Modified motors are obsolete. Just that in the larger boats the 700 motor is much better suited. For example a 16-23" vee bottom will run great with 6cells and a 05 motor, but will sink with the heavy weight of a 700 motor and 12cells! But a 30" vee bottom is much better suited to run a higher torque 700 motor, with a 05 motor will be underpowered and need many rebuilds because you would be pushing the 05 beyond its intended uses.