Re: [AMC-List] Funniest thing I haveseen in a long time- ELECTRIC TURBOS!

[Tom Jennings <tomj@xxxxxxx>]

On Thu, 2006-05-18 at 05:28, Frank Swygert wrote:
> I understand that, what I was getting at is if the turbo was connected
> to an air compressor instead of an engine it would still spin and
> create boost. But I see your point -- the heat in this case expands air 
> faster than a cool air stream would, so efficiency increases some.

Yes, but. In the air compressor example, there would be no "recovery" of
lost energy; you'get get out only what you put in (electric motor, etc).
i\In the turbo it's recovering the heat energy. The turbo efficiency
will drop with distance from the combustion chamber, no way around that.
If the temp. is lower the turbo will pump less. No way around that. This
is why turbos are more efficient (net energy consumed/produced) than a
belt-driven supercharger (though that might be more fun to drive :-)

If you could measure pressure and velocity at specific spots along the
exhaust system, you would see high temp/pressure close to the engine,
and less so as you get to the tailpipe. Clearly, contained by a metal
pipe, there's the same amount of gases at point A, B, C, ... all the way
down.

The pressure is dropping because the heat is exiting the gases by
radiating off the pipe.

(There's turbulence and other things going on, the gases swirling
chaotically down the length of pipe, eg. the source of exhaust
restriction and why you want a large one etc.)

If you insulated the pipe from the manifold down to the rear/under
mounted turbo, you'd get more power out of it.

> 
> On May 18, 2006 Tom Jennings wrote:
> 
> > On Wed, 2006-05-17 at 20:29, Frank Swygert wrote:
> > 
> > > I found this quote in the article, which explains why the remote
> turbo
> > > works -- pressure in the exhaust system (and volume of flow).
> Those
> > > thinking that the power is made by heat are just plain wrong. I
> never
> > > did understand how anyone can think that the heat makes the power
> in a
> > > turbo, it just doesn't make sense. I really don't see how heat
> > > increases efficiency either, since a cooler charge is denser and
> will
> > > create more power...
> > 
> > Actually fizzicks says so. The wasted energy in the exhaust is heat
> > energy -- why do you think it's exiting so fast! Gasoline + air +
> spark=
> > lots of heat which makes the gases get really big. If the exhaust
> > temperature was reduced (say, lots of refrigeration) to that of the
> > intake, the pressure would be the same too. Temperature makes the
> > pressure rise. Without the temp, no pressure.
> > 
> > Exhaust temp out of a turbo drops a lot too, representing the heat
> > energy extracted from the exhaust.
> > 
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