Grib said (snip...)
More (crankcase) vacuum means more HP, till you get to an amount that you
start pulling oil past the valves.
I just don't see how that can happen, Grib. (For simplification I leave out
both ram tuning on the intakes and exhaust). The pressure in the intake(at
WOT) should be close to atmospheric. And the vacuum you mention would be
throughout the valve covers as well as the crankcase. So the delta P will
always be preventing oil from being sucked "down" the valve guides. In other
words the vacuum around the valve stem is greater on the outside (under the
valve cover) than around the guide inside of any port. Remember, the ports
are sealed off from crankcase vacuum.
-Elon
Bryan Savage said (Snip...)
Using a dry sump will allow Me to do two things that will make a car run
faster. First you can run lighter oil safely. Switching from 20-50 to 10-40
can free up 2-6%, depending on the engine. . . The other is to use an
electric heater to pre heat the oil to 180 (+) degrees.
Bryan, you don't need a dry sump to run an electric heater. Heating
blankets are made that are bonded to the outside of the oil pan and can
pre-heat the oil to any temp you want. They are commonly used on any general
aviation aircraft (operating in cold climates) and wet sump drag racers.
Secondly, your suggestion of lowering the oil viscosity may be dangerous.
Bearing clearance is maintained by a phenomenon called hydrodynamic wedge.
The "thickness" of the wedge is influenced by the oil viscosity. Lower your
viscosity and you reduce the wedge thickness and run a greater risk of metal
to metal contact.
-Elon
Folks:
There are two kinds of dry sump pumps. The most common style uses spur
gears. The other kind is called a gearotor and is about 10% more efficient
that the spur gear type. Barnes used to make a gearotor type but no longer
does. Moroso is the only one (that I know) who currently provides a
gearotor style. A technician at Moroso said that my 4 stage pump uses about
20 hp. However, no RPM was indicated and I have no documentation on that
claim.
Mayf:
Dry sumps come in stages. 2,3,4,and 5 stage. You will not get a good
crankcase vacuum unless you use a 4 or 5 stage. Costs vary from $850 to
$1,300 depending on stages or brand.
-Elon
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