You can do it. But whether you have a 40-60hp electric motor driven by the alternator, or a conventional belt driven blower, or even an exhaust driven turbo, the fact is that part of the power it makes goes to driving it. In general, that power is around 40-60hp before an engine like the 3.5 is rendered into fragments of sharp, hot metal. (assuming a fairly efficient blower/turbo design)
An electric motor in that power range weighs a lot more than a simple belt drive, or all the ducting required for a turbo. And you would need an alternator that can produce 40-60hp to drive that electric motor, and that will weigh just as much as the 40-60hp electric motor.
Lighter, simpler, and a lot easier to maintain if you go with a traditional blower/turbo design. If you just want to go a 1/4 mile at a time, nitrous oxide would be the easiest of all.
And yes: without a device to pressurize the incoming air, an intercooler as they are currently designed would present a restriction to the airflow, and a net loss of performance.
I have to disagree on a couple points here, sorry.
Firstly, belt or electric driven forced induction is parasitic, yes, but turbo's are not. They use what is already being expelled by the combustion process, to create a hot pressurized air stream back to the intake.
An intercooler does exactly that, it cools the charge air, making it more dense. It's "basically" nothing more than another radiator for air instead of coolant.
They both work on the convection/heat exchange principle.
It may in fact restrict airflow to the rad., thus causing the car to run a little hotter, but it won't be a restriction to the intake system, turbo or not.
The sort of same thing a CIA does. Cooler air is more dense, thus being able to accept more fuel into the mixture, and ultimately the engine.
Turbo's are considered "free" horsepower as opposed to any other method of forced induction.
7000 HP top fuel cars require 1000 of that to spin the blower at the ratio they spin relative to the engine RPM. Net result of 6000 HP
7000 HP top fuel cars that would be Turbo'ed would suffer no parasitic loss, and only benefit by increased power.
Correctly built engines for the intended application of boost, will not result in fragments of hot sharp metal.
No, you can't "slap" on 30lbs. of forced boost to an otherwise stock engine, but neither can you "slap" on a 100 HP shot of nitrous to the same engine without risking failure.
Nitrous requires more fuel when in use, just like a blown or turbo'ed engine.
Saying it's easier and cheaper is a misnomer IMO, and just luring someone into engine failure from a lean condition if they don't understand, or are not educated on the "other" requirements needed to make it reliable.