On Wed, 22 Aug 2007 11:18:57 -0400, Gene Kearns
wrote:

An engine is, by definition, either naturally aspirated or not. If it
has a blower (supercharger) or turbocharger it is not naturally
aspirated.

http://en.wikipedia.org/wiki/Naturally-aspirated_engine

That may be true in a strictly technical sense, and true for all gas
engines and 4 stroke diesels, but "naturally aspirated" 2 stroke
Detroit Diesels are commonly understood to be without a turbocharger
since all DDs have a blower just to move air into the cylinders.

Gene Kearns:
If it
has a blower (supercharger) or turbocharger it is not naturally
aspirated.

Wayne.B:
but "naturally aspirated" 2 stroke
Detroit Diesels are commonly understood to be without a turbocharger
since all DDs have a blower just to move air into the cylinders.

Okay, I think I'm gettin' it now. I was thinking the DD "blower" was
just another term for "supercharger" but it's not.
The "blower" just provides the normal air pressure required to run the
engine (other 2 stroke designs do the same thing with crankcase
vacuum/pressure). But a "supercharger" would provide more than that.
An extra (super) boost so to speak. Thus the use of separate
terminology. Izat about right?

Rick

On Wed, 22 Aug 2007 14:01:49 -0500, lid wrote:

The "blower" just provides the normal air pressure required to run the
engine (other 2 stroke designs do the same thing with crankcase
vacuum/pressure). But a "supercharger" would provide more than that.
An extra (super) boost so to speak. Thus the use of separate
terminology. Izat about right?

Almost. Superchargers and turbochargers both generate boost pressure,
the difference is in how they are driven. Superchargers are direct
drive (belts, gears, etc), turbos are driven by exhaust pressure.

PhantMan wrote:
The "blower" just provides the normal air pressure required to run the
engine (other 2 stroke designs do the same thing with crankcase
vacuum/pressure). But a "supercharger" would provide more than that.
An extra (super) boost so to speak. Thus the use of separate
terminology. Izat about right?

Wayne.B:
Almost. Superchargers and turbochargers both generate boost pressure,
the difference is in how they are driven. Superchargers are direct
drive (belts, gears, etc), turbos are driven by exhaust pressure.

Right. Which is why I was confusing the "blower" term with a
"supercharger" rather than "turbocharger", since the blower is not
exhaust driven.
My ambiguous message up there was referring to the reason the DD
blower can be considered part of a "natually aspirated" system rather
than supercharged.
I somehow don't think I'm making sense today.

Rick