OK, so the only number we have is the 20hp test point. Here's a couple of
engineering comments----
1. The air pumping losses from the pistons may be more than you think.
Let's assume they are just blowing air like a fan. Assume for a minute a
432 cu in engine at 6000 rpm with the crankcase at atmospheric pressure.
OK, each revolution air equivalent to 432 cubic inches fills the cylinder
under the piston and then gets blown out. That means that in one rev 864
cubic inches of air is being blown around the crankcase like it's being
pushed by a fan working against no more than a fraction of an inch of water
backpressure. You can argue with the fan comparison; but I think it's valid
here.
864 cubic inches is 1/2 a cubic foot. At 6000 times per minute that is 3000
CFM worth of air movement in the crankcase. That's a lot of wind in that
small space. Looking at the Grainger catalog fans I see about 1/4 hp to
just circulate 3000CFM in free air, 1/2 hp to pump against 0.5 inches of
water and maybe 1 to 2 HP to build serious vent system pressures like 1 inch
of water. This is strictly fluid energy use. The friction losses in the
pistons (huge by comparison) aren't part of this comparison.
Bottom line here is that you may save one HP by running a sealed crankcase
under vacuum. OK, am I missing anything here?
2. With respect to dry sumps.....A gear pump stage running at 3600 rpm and
pumping 15 GPM of 30 weight oil at 210 deg F against a line loss pressure of
maybe 15 or 20 psi to an air separation tank will require at most 1/2 hp or
a lot less if there is lots of air in the oil. 3 of these stages won't
likely require more than 1 hp. The pressure stage will probably be doing
20-25 GPM at 65 psi for a little over 1 hp. But the pressure stage doesn't
count in this comparison. You have it whether dry or wet sump.
So if you believe my numbers the heavy hitter has to be the oil churning.
Ed Weldon
----- Original Message -----
From: <Askotto@aol.com>
To: <David.Freiburger@primedia.com>
Cc: <land-speed@autox.team.net>
Sent: Thursday, October 19, 2006 5:27 PM
Subject: Re: Dry sump oiling HP gains
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