As part of your research, I suggest you block off the outlet nozzle of the blower and put a PSI gauge on it. My guess is you won't get more than 0.5-1 psi. They work on flow, but if you stop that flow, usually they make very little pressure.
Engines make flow well enough on their own, hence why forced induction methods focus on pressure.
But NOW you're talking about some good ideas. No more tiny little heater blowers as "electric turbos." A dedicated 4hp blower on its own power supply might do some good
Granted it might only be 5 hp, but on a four-banger it might be quite noticable.
Not sure about the 12v blower. It might take as much power to run the alternator as it makes by blowing.
The only other snag I see is that if its a carbed car you'll need extensive carb mods to work under positive pressure, and if its an EFI car you'll need to hack the ECU and use a positive pressure MAP sensor.