GMC thingee

[Gary Derian]

Any supercharging device requires a reduction in compression ratio to limit
detonation.  That also reduces the expansion ratio which is where all the
power and economy comes from.  Crank driven superchargers are stuck with the
low expansion.  Turbine driven superchargers increase the expansion ratio at
the same time they increase the compression ratio.  This makes them
inherently more efficient while running boost.  Crank driven is OK for short
bursts of passing power if coupled with a de-activating clutch so parasitic
losses can be eliminated during cruise conditions.

Gary Derian <gderian at oh.verio.com>

<snip>
> Turbo and other devices still impose loss's on the system - you would be
> amazed how much of a restrictive loss that turd up your tail pipe is.
Unless
> you sell Pogue carbs - TANSTAAFL  ( There Ain't No Such Thing as a Free
Lunch
> - Heinlein ) applies and granted overall its less than the roots pumping
loss.
>
> But for fueling purposes, the roots tracks closely to a greatly increased
> displacement NA engine.   Most OEM EFI stuff can be set right over the
blower
> and not even suspect its blown - if they can flow enough fuel to match the
> air.  And the pulsing of a long duration cam is eliminated also - making
it
> easier.  And no sharply rising pressure curve to compensate for either.
The
> ease of fueling was part of the reason that turbos did not make major
inroads
> until the 80's.