turbo/supercharging

[Stephen Dubovsky]

...
>  you need it. The turbo offers the highest specific output potential of the 
>  two; it's more efficient (and more flexible) than a mechanically driven 
>  supercharger since it uses otherwise wasted exhaust gas energy. 
...

Now I don't want to start a flame, but you aren't getting something for
totally free here.  A turbo raises your exhaust back pressure (by as much
as the boost I seem to remember someone saying - or close enough;) and the
power your engine has to use to fight that back pressure is volume*dP.  And
guess what, the power reqd to compress the air at the intake is volume*dP.
Your engine has to work harder to get the exhaust out.  For ex: A 3.0L @
6000rpm w/ 1.0 bar boost and assuming 100%VE takes about 20-22kW of power
compress the air.  Neither a SC or TC is perfect (I seem to remember 60-80%
over a wide range) so your up to 25+kW.  This power comes from somewhere.
A SC takes it from the crank directly and a TC from the exhaust pressure.
Granted, the ~20 horses you lose will get you another 200+, so the net gain
is worth it;)  
SMD