(Don Klipstein) wrote in
:

In article , Ernie
Willson wrote in part:

It is true that turbocharging will increase efficiency and power output.
It is absolutely not true that anything that increases output per cubic
inch will increase efficiency. Supercharging is an example. It always
increases output and decreases efficiency.

How are the above all true if turbocharging is, as explained well by
Nate, a kind of supercharging?

- Don Klipstein )

From http://en.wikipedia.org/wiki/Turbocharging;

The objective of a turbocharger is the same as a supercharger; to improve
upon the size-to-output efficiency of an engine by solving one of its
cardinal limitations. A naturally aspirated automobile engine uses only the
downward stroke of a piston to create an area of low pressure in order to
draw air into the cylinder through the intake valves. Because the pressure
in the atmosphere is no more than 1 bar (approximately 14.7 psi), there
ultimately will be a limit to the pressure difference across the intake
valves and thus the amount of airflow entering the combustion chamber. This
ability to fill the cylinder with air is its volumetric efficiency. Because
the turbocharger increases the pressure at the point where air is entering
the cylinder, a greater mass of air (oxygen) will be forced in as the inlet
manifold pressure increases. The additional oxygen makes it possible to add
more fuel, increasing the power and torque output of the engine.


the "efficiency" gained is VOLUMETRIC efficiency.
"size-to-output efficiency".
meaning the motor acts like it is of much larger displacement.

turbocharging uses the wasted energy of the hot exhaust to compress the
intake charge,while supercharging is a parasitic drag all the time.

--
Jim Yanik
jyanik
at
kua.net