beware VW turbo repair scham

JS> I SEE NOTHING in that article that supports your inane statement.

Below are quotes from the article:

"A disadvantage in gasoline engines is that the compression ratio
should be lowered (so as not to exceed maximum compression pressure and
to prevent engine knocking) which lowers engine efficiency when
operating at low power. This disadvantage does not apply to
specifically designed turbocharged diesel engines.

Turbocharging is very common on Diesel engines in conventional
automobiles, in trucks, for marine and heavy machinery applications. In
fact, for current automotive applications, non-turbocharged diesel
engines are becoming increasingly rare. Diesels are particularly
suitable for turbocharging for several reasons:

Naturally-aspirated diesels have lower power-to-weight ratios compared
to gasoline engines, turbocharging will improve this P:W ratio.
Diesel engines require more robust construction because they already
run at very high compression ratio and at high temperatures so they
generally require little additional reinforcement to be able to cope
with the addition of the turbocharger. Gasoline engines often require
extensive modification for turbocharging.
Diesel engines have a narrower band of engine speeds at which they
operate, thus making the operating characteristics of the turbocharger
over that "rev range" less of a compromise than on a gasoline-powered
engine.

fbloogyudsr wrote:
>
> NONONONONONO! You need to take some physics courses.
> TANSTTAAFL. Every bit of HP you get out of an engine takes
> *MORE FUEL*. Period. Exclamation point.

That's obviously wrong. Simple experiment: turn the
distributor on a carburetor car. The fuel consumption
says the same but the HP you get for that fuel changes.

This is because if the timing is wrong then the fuel will
not be burnt correctly (remain unburnt, or undergo less
efficient combustion). I'm sure you know this ?

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.

1. (5 marks) What is the benefit of increasing the air pressure
inside the cylinders? _______________________________________

2. (2 marks) Does this increase fuel consumption? [ ] Yes [ ] No

Magnulus wrote:
> "fbloogyudsr" > wrote in message
> ...
> > NONONONONONO! You need to take some physics courses.
> > TANSTTAAFL. Every bit of HP you get out of an engine takes
> > *MORE FUEL*.
>
> If that were true, then engines would never get more efficient.
>
> >
> > The only way that you get a little better mileage out of a car with
> > a turbo diesel rather than a normal diesel *OF THE SAME HP*
> > rating is because the turbo engine is smaller and hence the
> > car supporting it is lighter and has less rolling resistance.
>
> The turbodiesel engines in the current TDI's are bigger (1.9 liter-100-110
> hp) than the diesel engine from the 1970's and 80's (I believe they were 1.5
> liter- 50-70 hp), yet the fuel consumption is about the same. And the VW
> diesels from the 70's and 80's weighed over 1000 lbs less (the old
> Golf/Rabbit weighed about 1900 lbs., the current Golf TDI weighs about 3000
> lbs)

If you were to step back a minute and compare the -same- car with the
same engine, with and without a turbo you just might get what everyone
is telling you (although I doubt it). Turbos do not increase
efficiency (measured in mpg) they actually use more fuel. 2LOT
explains it: "You can't win, you can't break even and you can't even
get out of the game"

Harry K

Harry K wrote:
>
> Magnulus wrote:
>
>>"fbloogyudsr" > wrote in message
...
>>
>>>NONONONONONO! You need to take some physics courses.
>>>TANSTTAAFL. Every bit of HP you get out of an engine takes
>>>*MORE FUEL*.
>>
>> If that were true, then engines would never get more efficient.
>>
>>
>>>The only way that you get a little better mileage out of a car with
>>>a turbo diesel rather than a normal diesel *OF THE SAME HP*
>>>rating is because the turbo engine is smaller and hence the
>>>car supporting it is lighter and has less rolling resistance.
>>
>> The turbodiesel engines in the current TDI's are bigger (1.9 liter-100-110
>>hp) than the diesel engine from the 1970's and 80's (I believe they were 1.5
>>liter- 50-70 hp), yet the fuel consumption is about the same. And the VW
>>diesels from the 70's and 80's weighed over 1000 lbs less (the old
>>Golf/Rabbit weighed about 1900 lbs., the current Golf TDI weighs about 3000
>>lbs)
>
>
> If you were to step back a minute and compare the -same- car with the
> same engine, with and without a turbo you just might get what everyone
> is telling you (although I doubt it). Turbos do not increase
> efficiency (measured in mpg) they actually use more fuel. 2LOT
> explains it: "You can't win, you can't break even and you can't even
> get out of the game"
>
> Harry K
>

But the "same" car with a NA engine with the same power output as the
turbo... now you have much greater efficiency with the turbo, for
various reasons.

I'm not really certain your assertion is valid - I imagine the BSFC
curve ought to be fairly similar for a well-designed turbo implemetation.

nate

--
replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel

> But the "same" car with a NA engine with the same power output as the
> turbo... now you have much greater efficiency with the turbo, for
> various reasons.

which reasons would these be?

JohnH wrote:
>>But the "same" car with a NA engine with the same power output as the
>>turbo... now you have much greater efficiency with the turbo, for
>>various reasons.
>
>
> which reasons would these be?
>

first and foremost the lighter weight of the turbo engine giving a much
more favorable power/weight ratio...

nate


--
replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel

Harry K wrote:
>
> Turbos do not increase efficiency (measured in mpg) they actually
> use more fuel. 2LOT explains it: "You can't win, you can't break
> even and you can't even get out of the game"

The relevant law here is 1LOT (conservation of energy).
In that quote, "You can't win" refers to 1LOT and
"you can't break even" refers to 2LOT (the law of entropy).

"Old Wolf" > wrote
> fbloogyudsr wrote:
>>
>> NONONONONONO! You need to take some physics courses.
>> TANSTTAAFL. Every bit of HP you get out of an engine takes
>> *MORE FUEL*. Period. Exclamation point.
>
> That's obviously wrong. Simple experiment: turn the
> distributor on a carburetor car. The fuel consumption
> says the same but the HP you get for that fuel changes.
>
> This is because if the timing is wrong then the fuel will
> not be burnt correctly (remain unburnt, or undergo less
> efficient combustion). I'm sure you know this ?

We've been assuming an engine in tune. But that isn't
the point I was making. The compression (expansion)
ratio of any engine - gas, diesel, methanol, etc. - is the
limiting factor where efficiency is concerned.

Floyd

Nate Nagel wrote:
> JohnH wrote:
> >>But the "same" car with a NA engine with the same power output as the
> >>turbo... now you have much greater efficiency with the turbo, for
> >>various reasons.
> >
> >
> > which reasons would these be?
> >
>
> first and foremost the lighter weight of the turbo engine giving a much
> more favorable power/weight ratio...
>
> nate
>
>
> --
> replace "fly" with "com" to reply.
> http://home.comcast.net/~njnagel

Did you forget the "same engine" bit? How does adding a turbo to an
engine make it lighter? A turbo squeezes more power out of an engine
and the only way you can do that is use more fuel. There is no device
that yeilds an over-unity result (more energy out than you put in).

Harry K