[Land-speed] Dry Sump

Elon saltfever at comcast.net
Wed Dec 31 20:39:44 MST 2008


Chris:

I imagine it has to do with oil's high surface tension. In this case a
square has more area than a round tube and attracts oil, via surface
tension, to the pickup area. Or you are distributing the pressure drop over
a large area, meaning a lower velocity into the entrance of the tube. Lower
velocity should have a greater probability of laminar flow with less
turbulence. A bell-mouth tube (like injector stacks) may have as much
surface area and be even better than the square with non-turbulent flow;
however, it would locate the tube entrance too high off of the floor of the
pan (leaving too much oil on the floor) which is the antithesis of a dry
sump.  Putting the bell-mouth entrance on the bottom of the pan adds too
much height (due to plumbing underneath) to an engine package that is always
trying to be lower in CG. However, in your case you state a deep pan is fine
so tubes coming out of the bottom may be ok. I realize serious credence
should be given to current practice because beaucoup R $$ D has been put
into the square pick-up. However, those systems are optimized for race
courses that deviate from a straight line. Why not do a test? Machine both
kind of ports into a piece of lexan and run your pump with a cordless drill
and watch what happens. Let us know the results. Oh! and Happy New year
Chris :-)  -Elon  USD$.02



Original Message (snip . .. )

For the scavenge pick-ups in the bottom of the pan, which work best, a boxed
pick-up with a filter screen

or just scavenge tubes with external line filters outside the pan.



The boxed pick-up style most common, so is there some fluid dynamics at play


here, or just the better way to filter.


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