That was a good thread. I enjoyed reading the messages. I would like to
throw out some additional thoughts regarding the use of vacuum pumps.
And I am. heaven knows, no expert, barely a novice. When the engine is
running at full boogie the piston speeds are pretty high somewhere in
the neighbor hood of 4000 ft per minute or about 67 ft per second. The
bottom side of the down going piston is pushing the air out of the way
at that speed for an instant or 2. And because the air is laden with oil
mist and droplets, the density of the air is effecitively changed. And
that air/oil mixture has to be started and stopped each reciprocation of
the piston. So, I do not think it is as simple as figuring the cfm
because the mass of the air is not being considered. And power will
require the mass be known. I think. And you must consider that there is
a lot of stuff in the way of the air as well, things like the crank, the
rods, main webs that the air has to go around in going from one cylinder
to the next. And while air is compressible, it is pretty mush not at
these speeds. Also the temperature of the mixture has to be considered
as well; as temp goes up, density goes down for a given pressure. When
vacuum is applied, the mist tends to fall out because there is less to
keep it floating around. This lowers the effective air mass so pumping
is easier freeing up some hp. What I use my simple evac system for, it
to collapse all the bubbles in the air. The turbos beat the oil to a
froth and this goo enters back into the oil pan and mixes with the good
stuff. I figured that collapsing the air bubbles has to be good. Does it
provide extra hp? Maybe a teensy bit. Does it help? yeah I think so in
egards to helping the oiling system provide a solid stream of oil. Is it
worth it? To me, yes. You, maybe not.
I would love to see some more data regarding the hp gains and losses for
both multi stage dry sump and single stage wet sump. Seems like the dry
sump pump makers would have data with regards to how much it takes to
drive the various pumps-- anybody ask them? And, I know it is almost
sacreligious to take on heating the motor... There was a recent article
in the NAtional Dragster that said if the air temps were above 90
degrees or so, there was absolutley nothing to be gained by heating the
motor by running it. Is this right? WHo knows, just data and info.
mayf, back for a 40th year reunion and homecoming at Cal Poly in SLO.
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