Newsgroup: it.discussioni.auto
Titolo: Sembra di leggere CMC :-)))

Sembra di leggere CMC su alt.autos.porsche911, questo si occupa di
motore aeronautici e si parla di consumo d'olio del flat six :-)))
Spero non vi dia fastidio questo corposo cut & paste, ma mi ha stupito
leggere che questo ha una 911 2,4 con 233.000 miglia (372.000km circa
:-OOOOOOOOOOO)
- - - - - - - 
I quart sounds a little much. Check it out yourself. Drive the car
after an
oil change.
What does the manual say? My 1972 911T 2.4L said specifically that the
engine may use as much as 2 qt's ever 600 miles and not be excessive.
The
cylinders were right at the maximum taper when I rebuilt the engine,
and it
smoked a little and used about 1 qt in 1,000 miles. The engine bore
and
crank were still within the standard specification when I overhauled
it at
230,000 miles. I put another 100K on it before I sold it and it still
exhibited the same usage the 14 years I had it. It would smoke at
start up
when it needed an oil change. The engine seeped, like every Porsche
that has
any time on it or has oil in it...
But my 1991 C2 3.6L seeps a little and I could add a qt at oil change
interval of 5,000 miles.
If you read anything by Bruce Anderson you will see that these flat
six's
all use/seep/and some smoke from time to time. Bruce Anderson has
forgot
more about Porsche's that we collectively know.
I am an Aircraft Mechanic A&P as well as a Mechanical Engineer. I have
been
around many Air-cooled engines, radial and opposed. When you plan a
trip in
an reciprocating aircraft, you always consider adding oil during the
trip.
What it comes down to is that air-cooled engines can have a greater
tolerances between the working parts. This increased dimension is due
to
coefficient of expansion differences between the piston and the
cylinder,
etc. These engines grow as they warm up, the growth is different
between the
different materials. Aluminum grows more than steel.
Look at the problems Porsche has had with a few engine types with
Dilvar
Head studs. Some engines came with Dilvar studs along the bottom, and
not
the top row, while some profess that the engines need Dilvar top and
bottom,
while others say that the Dilvar studs are to brittle and the best
thing is
to use the Raceware studs. This is all do to the engine growth during
the
warm up cycle. I am not sugesting that your engine has stud problems,
just
using this as an example of air cooled engine properties.
Bottom Line, most Air-cooled use more oil that a water cooled engines,
and
Porsche Air-cooled engines will use some oil.
Excerpt form my 1991 Carrera 2 Manual:
Page 68, Engine Oil
Engine oil consumption
It is normal for your engine to consume oil. The rate of oil
consumption
depends on the quality and viscosity of oil, the speed at which the
engine
is operated, road conditions as well as the amount of dilution and
oxidation
of the lubricant. Because of these variables, no standard rate of oil
consumption can be established, but drivers should expect increased
oil
consumption at high speeds and when it is new.
I have also found that some oils make the engine smoke at start up
more than
others. Find an oil that does not smoke and fits your driving
conditions and
keep an eye on the oil level. I have also found that on my '72, it was
best
to keep the engine oil level 1 qt above the red line. I seemed to me
that
over that amount the oil was used at a higher rate.
I wouldn't use any modifiers like STP. I found that 30wt worked best.
10-40
and 20-50 grades allow the oil to drain into the cylinders via the
worming
around the rings. I
do not have any physical proof of this, just a hunch...
If you still think the engine is using too much oil, I would have a
mechanic
perform a "Cylinders Leak Down Test". This is done with a unique
device and
an outside pressure source. The device has a pressure regutator, two
pressure gauges, and air flows through a sized orfice into the
cylinder at
Top Dead Center (TDC). The standard inlet is 80 psig, and the pressure
held
in the cylinder should be within 85% of the inlet pressure. Any leaks
can be
heard through the exhaust, or intake manifold, or even the oil filler
neck.
Anyting below that value my indicate excessive cylinder or fing wear.
This
test is far more conclusive that a standard cranking compression test.
The
leaking past the rings is called blow-by and increases the pressure
inside
the crankcase which leads to external leakage. This is also where
excessive
oil dilution comes from if the engine is running rich.
 Work on sealing any leaks, keep an eye on the oil and have fun with
the
Porsche.
Keith Williams
Lorenzo "Huhi" Corsani (FI) (25,150,5-140-231) 
Driving and loving Coupč20V, 911 Carrera 3,2, Clio16V
N2K Compliant


A me non ha dato fastidio ;-))
Anche a me piacerebbe avere 2 911, quella da uso quotidiano e quella dura e
pura da divertimento ...... una bella 911 3.3. Turbo, magari elaborata di
brutto ;-PP
--
Ciao, Davide "Fuoribordo" (made in CMC) (38,272)
N2K Compliant driver (
http://ida.nurburgring.it
)
ICQ 10727763
Hai mai visto la mitica Shelby Cobra? 
http://www.rgmconsultants.it/auto
"l'auto del nonno"

brutto ;-PP
Copioooooooooneeeeee :-PPPPP
L'idea del 930 da pista è miaaaaaa :-))
Albert
Help Desk Delta integrale.  :-)))
=
Albert  (27, 107, BL)
Punto Sporting Driver 
Lancia Delta Evo Dreaming
N2K Compliant
IDA Icq active list nr 66230517
ICQ: 24843883
=

motore aeronautici e si parla di consumo d'olio del flat six :-)))
La Porsche ha derivato dal flat six un motore aeronautico.

La Porsche ha derivato dal flat six un motore aeronautico.
INfatti, se non sbaglio si tratta del 3.6 della 964 :-) Ricordo il
piccolo biposto con la scritta POrsche :-)


brutto ;-PP
magari un targa, 489 esemplari costruiti in tutto :P