Why the electric superchargers as advertised on ebay don't work.
We will just look at one example and will use the 3.8 V6 Ecotec which is a pretty common engine.
Such an engine if it had 100% volumetric efficiency and you were to give it wide open throttle will draw 3.8 litres of air in two revolutions of the engine.
Say it idles at 700rpm that is 1.9litres/rev by 700 = 1330litres per minute.
Now we increase the rpm to 1500 = 1.9 by 1500 = 2850litres per minute.
Now lets jump up a bit to 4000 rpm = 1.9 = 7600litres per minute.
You will see that the at only 4000rpm the air volume has increased 7 times from idle. Will these puny electric superchargers which draw (from one advert at least) 35 amps = 420watts be capable - no way. As with a supercharger this electric motor is sucking power out of the engine in order to provide some. The photos I have seen on the net show the electric supercharger to be far too small to have a hope of providing a boost that would feed a 1.5 litre engine let alone a 3.8 litre.
An engine driven supercharger increases speed and volume with engine speed and so does a turbo charger. Any electric motor would have to be capable of drawing a lot of amps which would flatten the battery if it could keep up with demand from the commodore engine without even being able to provide boost pressure. As in the example above the electric motor would have to be capable of increasing its operating speed 7 times to keep on top of things without becoming a liability to intake volume. Electric motors if overdriven start to become generators and oppose the additional rpm.