I posted this on the wrong thread the other day LOL
It was meant for this thread (better late then never)!!
Here it is
Positive-displacement or "Roots-type" superchargers tend to produce massive power at low rpm and taper off higher in the rpm range; from Idle to about 5500 Rpm on a low boost engine which is usually on the street or a weekend warrior!
You converter and cam don't come in till late and are wasting all your torque your putting out at your lower RPMs with a roots supercharger. Right off idle an engine with a Roots supercharger will typically have nearly full boost and massive power. This power increase will be fairly constant throughout the RPM range. Till it reaches an rpm point that the supercharger begins to lose efficiency!
Turbos are the other way around! low boost at idle and as rpm comes up boost increases to high rpm so you need high stall speeds and cam's that come in late!
Sorry its late LOL