In a message dated 10/19/2006 10:29:07 A.M. Mountain Daylight Time,
Saltrat@lubricationdynamics.com writes:
OK Otto,
Please explain to me how it is free HP when you trade one oil pump
for three (or at least two) which take power to turn them and you add
about 50 or 60 lbs to the car at least which takes power to move down
the track.
Hi Skip
In a normal wet sump system, compression blow by creates a pressure in the
crankcase. This pressure causes a resistance to the pistons going down in the
bore on the power stroke. Having a blower or in your case, twin turbo's,
increases the pressure in the crankcase even more. Yes, you have breathers but
pressure still builds up.
The dry sump system on the other hand creates about 15 inches of vacuum in
the crankcase. This "sucks" the pistons down the bore. This is where the HP
gains are actually realized.
There is also the theory that the vacuum increases ring seal against the
cylinder walls and keeps oil from squeezing out the gaskets, seals, etc. Also
with oil scavenging in the lifter valley, you don't have oil coming down to
get
wound up in the crankshaft. The oil hitting the crankshaft causes HP losses.
That's another reason I always run a crank scraper and a well designed
windage screen around the crank. It all adds up to more HP.
Drag race engines that don't run dry sumps have vacuum pumps to create the
vacuum in the crankcase for more HP.
As I recall the HP gains just going to a dry sump system are around 20 HP.
Otto
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