beware VW turbo repair scham

I agree...that is a poor design.

Magnulus wrote:
> The VW TDI's use the turbo even with light acceleration. The turbo
> does increase fuel economy because it reclaims waste energy from the
> exhaust and uses it to pressurize the air inside the cylinders. Most
> diesel engines for cars or trucks, or even busses, have turbos.

What's this now? They reclaim "waste energy"?

Please explain!

(I gotta hear this one! )

Perpetual motion machine.....

JohnH wrote:
> Magnulus wrote:
> > The VW TDI's use the turbo even with light acceleration. The turbo
> > does increase fuel economy because it reclaims waste energy from the
> > exhaust and uses it to pressurize the air inside the cylinders. Most
> > diesel engines for cars or trucks, or even busses, have turbos.
>
> What's this now? They reclaim "waste energy"?
>
> Please explain!
>
> (I gotta hear this one! )

I know this has *GOT* to be a troll, but I'll bite anyway...

It lets the exhaust, which is still warm, expand and cool in the
turbine instead of when it leaves the tailpipe, thus using that energy
that would otherwise be wasted do useful work (i.e. overcome intake
pumping losses.)

nate

wrote:

> My S4, if I keep it under 2200, it's not on-boost. I can (if I am very
> disciplined) get 27mpg out of that car in mixed driving.

Seriously? I have an S4 as well and I've never been able to achieve
more than 22 to 23 mpg in mixed driving. If I drive mostly on the
highway, I get a maximum of 28 mpg and typically around 25 mpg. If I
drive mostly in the city, I'm lucky to get more than 19 to 20 mpg (and I
don't really accelerate that fast).

Of course, there are plenty of steep grades on the highways where I am
which require using boost.

Arif Khokar wrote:
> wrote:
>
> > My S4, if I keep it under 2200, it's not on-boost. I can (if I am very
> > disciplined) get 27mpg out of that car in mixed driving.
>
> Seriously? I have an S4 as well and I've never been able to achieve
> more than 22 to 23 mpg in mixed driving. If I drive mostly on the
> highway, I get a maximum of 28 mpg and typically around 25 mpg. If I
> drive mostly in the city, I'm lucky to get more than 19 to 20 mpg (and I
> don't really accelerate that fast).
>
> Of course, there are plenty of steep grades on the highways where I am
> which require using boost.

I did it once. Driving like a total granny. The really ****ty thing
was that I was *still* held up by folks slower than me.

Most of my commute is highway-type speeds now. I get about 25mpg.
Oddly, my wife gets less with the Avant - but two tons of steel, just
around town - I'm glad she gets over 20.

E.P.

"John S." > wrote in message
oups.com...
> Perpetual motion machine.....
>

Not more so than a hybrid car. Turbo doesn't make extra energy, but if
you think there's no potential energy in exhaust gasses, well, you are
wrong.

> Not more so than a hybrid car. Turbo doesn't make extra energy, but
> if you think there's no potential energy in exhaust gasses, well, you
> are wrong.

Sure there is, but a turbo does nothing to take advantage of it.

From http://auto.howstuffworks.com/turbo2.htm :

"One cause of the inefficiency comes from the fact that the power to spin
the turbine is not free. Having a turbine in the exhaust flow increases the
restriction in the exhaust. This means that on the exhaust stroke, the
engine has to push against a higher back-pressure. This subtracts a little
bit of power from the cylinders that are firing at the same time. "

So, even though you can get more *power* from a turbocharged engine, it's
less efficient at typical alititudes. For example, the Subaru Outback 2.5L
4 cyl loses 3-5mpg when you strap a turbo on it.

"JohnH" > wrote in message
...
> > So, even though you can get more *power* from a turbocharged engine,
it's
> less efficient at typical alititudes. For example, the Subaru Outback
2.5L
> 4 cyl loses 3-5mpg when you strap a turbo on it.

Diesel don't lose any fuel economy from having a turbo, in fact they gain
fuel economy from the turbo. You lose some power to a restrictive exhaust,
but you gain it back through the turbocharger, and then some.

Most big trucks and busses have turbos. Fuel economy is the name of the
game for these kinds of vehicles- a trucking company can spend almost as
much money on fuel as labor costs. If turbos lead to worse fuel economy,
they wouldn't use them.

"Magnulus" > wrote
> "JohnH" > wrote
>> > So, even though you can get more *power* from a turbocharged engine,
> it's
>> less efficient at typical alititudes. For example, the Subaru Outback
> 2.5L
>> 4 cyl loses 3-5mpg when you strap a turbo on it.
>
> Diesel don't lose any fuel economy from having a turbo, in fact they gain
> fuel economy from the turbo. You lose some power to a restrictive
> exhaust,
> but you gain it back through the turbocharger, and then some.

This is an absolutely crap statement. Take any engine and put it in a
vehicle
and measure it's fuel economy. Then add a turbo. The economy *will* go
down: you never get something (more power) for nothing: 2nd law of thermo-
dynamics at work.

> Most big trucks and busses have turbos. Fuel economy is the name of the
> game for these kinds of vehicles- a trucking company can spend almost as
> much money on fuel as labor costs. If turbos lead to worse fuel economy,
> they wouldn't use them.

No. You get more *power* out of a smaller engine. If you had to put
a non-turbo engine that got the same power (remember, you need the
power to haul the goods - it doesn't do any good to deliver rotten food
to the market), the tractor would be too heavy and your payload would
suffer.

Floyd