Saab: Ok, can somebody please tell me the advantages and disadvantages of turbo?

On Sun, 25 Jan 2004 05:18:39 GMT, Peter <com> wrote:
 

Positives, smaller engine needed, higher power output when turbo kicks
in. When turbo kicks in, fuel consumption goes up. Without turbo,
fuel consumption is much better.

Disadvantages: lag in turbo power boost, since it is run from the
exhaust gasses (there are mechanisms to make this somewhat better).
Mechanical complexity, it's another piece of equipment. Car will need
more frequent oil changes, but that's only good maintenance anyway.
(not more frequent than 3000 miles). Turbo has a limited lifetime,
and will eventually require replacement. (yet another thing to
break).

 

They're not. Mercedes has them, Subaru has had them, Volkswagen (I
think) might have had them. Mitsubishi, Ford, Mazda have had them
(Ford Probe GT, 1989 to about 1993 or so, GT model). Mitsubishi
Eclipse, mostly any GX, I think.

Saab is the only manufacturer that makes the turbo standard on all
models, iirc.

Two varieties, depending on how much boost (additional air pressure)
you have. LPT and HPT. LPT generally (2000 9-5, for example) does
not have a turbo pressure gauge. engine is a 2.3t (small t), HPT has
more boost, higher horsepower, and is a 2.3 T.

Higher boost generally means more engine power.

(note: had an 89 probe GT, loved the car. Had mitsubishi 98 eclipse
without turbo... was really dead.) Father had 200D (diesel, turbo)
Mercedes... had very bad turbo lag, (dead to 2500 rpm, then zoom after
it), have 2000 9-5... much nicer.

Harvey
 

Harvey White wrote: 

For normal driving, fuel consumption with turbo is better. This is
because the engine is more efficient and more torque is available at
low RPM. If you use the extra performance, then yes you have to pay
for it.
 

No noticeable lag in LPT, (light pressure turbos). These are designed
to take advantage of the turbo for improved driveability at low RPM.
Turbos last well (> 100,000 miles) if treated with a minimum of care.

 

The VW 1.8T engine goes into VW, Audi, Skoda and Seat. Rover also have
a 1.8T which replaces their 2.5V6 and has identical performance, but
with lower fuel consumption and emissions. Vauxhall (of course Saab's
cousin). Mercedes use a different system (Kompressor) to get positive
displacement. Most car diesels from all manufacturers use turbos.
 

Was! Saab now also have non-turbos: 9-3 1.8i and 9-2 2.5L
 

See above.

On Sun, 25 Jan 2004 05:37:03 GMT, Harvey White <netcom.com> wrote: 

Yes - you get more power (and the correspondingly higher fuel consumption)
when you're getting heavy on the "loud pedal", but when you're driving
normally you continue to have the fuel efficiency of the small engine.
 

The recent generation of turbo that Saab uses has a "low mass" configuration
so it spins up much more quickly than the turbos of the 1970's, but it's
still noticable. I'm not sure it's _bad_, just that it's noticable.
 

I'm not sure I agree with this statement. The turbos are robust; it's not
a normal wear item that you have to plan to replace or anything. My '88
900 Turbo still had (has?) the original turbo in it, when I traded it
in at 247,000 miles, and the only "unusual" thing I did was use synthetic
oil throughout my ownership of the car. Hearing about a turbo failure in
a saab isn't by any means a common thing, going by this group's history
and so on.
 

Also, turbos are widely used in the diesel trucking industry, for pretty
much the same reasons - better fuel efficiency and power.

Dave Hinz

>What is the positives with turbo and are there any drawbacks? 

Turbos have come and gone in other cars, usually billed as a performance item.
They haven't been all that reliable for other manufacturers.
Saab, on the other hand, has been using turbos forever and has it figured out.
I've got a 1995 9000 LPT. With the turbo, I've got the economy of a 4-cylinder
with the power of an 8. I traded in a Lincoln Mark VIII for the Saab and don't
feel I lost anything at all on power, except in the 90mph+ range -- a range I
don't visit much.
My "around town" gas mileage in the Saab is 26-27 mpg, 31-32 for straight
highway driving. The Saab runs well on mid-level and even regular, while the
Lincoln required premium and only got 14 mpg around town, 24 highway.
I test drove a regular turbo and the LPT when I bought the car. The power curve
on the LPT is the most useful.
Most important, the turbos are fun to drive!


com
http://www.madmousergraphics.com
web design, print design, photography

Thanks to all who answered my question on turbo. Feel a lot better
about that now!

Now two follow up questions:

What is the quality of Saab, the newer generations in particular.

I am interested in the 9-3, convertible so another questions would
be what is the consensus on Saab convertibles?

Just for comparison, I have a Mustang convertible right now and it is
working ok but it took most of the 36k warranty to get all the quirks
out of it.

Thanks again for taking time to respond to my questions!

-Peter

On 25 Jan 2004 15:09:28 GMT, Dave Hinz <net> wrote:
 
<snip> 

Agreed, they are, but I was speaking in an absolute sense. Older cars
needed more frequent oil changes with "turbo" oil (SF or SG rated for
the probe, for instance). I always changed mine more frequently, and
tried to let the turbo cool after a run. I also tried not so drive
with my foot in the turbo. What "broke" on it is that the seal to the
engine is going, so that's a problem.

I've seen reports of some turbos going bad in Saabs, but I'm not sure
which models, and which model years.


 

yep, no data there, though. I can speak about the cars above, probe,
eclipse, vw (no turbo), and mercedes diesel.

Harvey

 

I don't think anyone can produce any statistics that show that turbos have
some designed-in reliability issue. Engineering book in hand, there's no
reason why they should. The "more moving parts" does not hold water when
keeping in mind turbos are actually very simple mechanical devices, and that
the altrnative is a V6 or V8 with *far* more moving parts subjected to far
more mechanical stress than turbos, which merely spool in very predictable
fashion. Cylinder heads and valves are subjected to far higher temperatures
and pressure, just as an example.

Turbo engines are extensively used in aviation, which is not known to take
on design and reliability risks. Almost every propeller plane uses a turbo
engine. The reasons point at the basic key advantage: more power, less
weight. The only disadvantage of a turbo in an automotive application is the
famous lag, but it's been engineered down to a minimum these days. The other
one is the engine noise when the engine is pushed, but typically one wants
some noise when flooring the throttle. On the other hand, in cruise mode
many turbo engines are eerily quiet (the Saab's is). The noise is a bit more
agricultural than a Beemer's I6 under load. Other V6 engines do not compare
as favorably, in my opinion.

....pablo

And with the addition of one part and swapping another, you would blow
by the Mark VIII! LPT to FPT conversion on the 9k is a painless project
I have done twice. I prefer the LPT as a used car because they were not
beat upon as much.

As the the original poster's question. The performance/economy issues
have all been covered. A turbo is not a negative but a plus. The 9^3 has
modern engine management and hardware which minimize the 'lag' that
people talk about and with periodic oil changes (3-4k) the turbo should
last 200kmi or more. With synthetic, it should last much longer than
that. If the maintenance is neglected on it, though, your guess is as
good as mine as to longevity.

I have 130kmi and 115kmi on 2 of them now and a friend has one with
275kmi on the original turbo.

KeithG

LauraK wrote: