The formula 1 boys have been running hybrid engines with engines using a supercharger "boosted" by an electric motor for 5 years now. Apparently that's how long it took for their electric motor technology to make it to consumer market.
There has been some speculation that one of the manufacturers was getting around the rules limit of 160 kW (214 hp) of battery power addition, by using battery power to spool up the supercharger which wasn't being monitored...
From their graphs, their supercharger will get you 20-25 hp gain for 2 minutes or less. Is that worth $2,500 to you?
if I calculate correctly at this late hour:
5000 watts is about 6.7 hp, and that little motor is gonna get hot real quick.
it's a good thing they use a power pak to bump the volts up to 48, because to
get 5000 watts at 13.5 vdc would need about 370 amps.
I thought about using a boat bilge blower (they are a electric in-line blower fan for engine compartment ventilation in stern drive boats) in a car over 20 years ago, worked at a boat dealership at the time and had salvaged all the needed parts from junked boats. turns out those dont move enough air. I was only in my early 20’s then.