[Vwdiesel] Turbo vs. Non-turbo [was My TURBO test (more scien tific)]

[Shirley, Mark R]

> -----Original Message-----
> From: Tyler "Casioqv" Backman [mailto:casioqv at usermail.com]

> What you are trying to say is that for some reason _all_ engine
> manufacturers put a turbocharger on for just one reason, and do not
> consider many of the other advantages and disadvantages when they make
> their decision? Even ones that would affect sales more than the
> efficiency or peak power output?

I didn't get the email before this one, but I can comment here.  All
diesel engines for sale ON ROAD today will have a turbocharger on it
for the simple reason of emissions.  You simply cannot make emissions
levels required without one these days.  You can be sure though, they
do use the turbo for marketing!  There's simply no option anymore on this
issue.


 If all diesel engine
> manufacturers were
> complete morons, than why do many of the engines sell so
> well, and work
> so good?

Diesel engines sell well because they are durable, and in business
applications, FUEL EFFICIENT.  Joe Businessman usually doesn't care
how fast his employees can get from point A to B (within reason) but
the fuel economy of the vehicle is usually tied to his BOTTOM LINE.


I am
> sure that every design decision they make is made based on
> many factors,
> none of them are inadvertent side effects that were never considered.
> What my main point was, is that there are very few reasons to not
> turbocharge a diesel engine, other than cost.

How true.

> That is not what I said. What I said is that increased thermal
> efficiency can lead to gains in both horsepower and torque,
> or just one
> or the other depending on the setup.

Torque.

A Turbocharger does not violate
> conservation of energy, but does increase efficiency because
> most of the
> power that drives it comes from the exhaust heat energy, which is
> otherwise wasted. Some energy comes by increasing backpressure to the
> engine, and therefore decreasing the power output of the
> engine,

Most of the backpressure increase is overcome by the VE increase/boost.  The
net effect
is very slight.

but not
> most of it, and certainly not all of it. Do not underestimate how much
> of the energy in a diesel engine is "wasted" as heat, it is a
> very large
> percentage,

Rule of thirds:  30% exhaust waste heat, 30% coolant waste heat, 30% power,
Remainder,
frictional and other losses.

>