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RE: high milage fluids

To: Dan Walters <spridget63@comcast.net>, "'Robert E. Shlafer'" <PilotRob@webtv.net>, "'Patricia Sauthoff'" <trishasauthoff@yahoo.com>
Subject: RE: high milage fluids
Date: Sun, 12 Jan 2003 06:20:16 -0800 (PST)
Cc: "'spridgets'" <spridgets@autox.team.net>
--- Dan Walters <spridget63@comcast.net> wrote:
> Right!  Synthetics were designed for use in turbine
> engines that turn a
> heck of a lot more rpm than any race engine ever
> could and will "stick"
> to these parts at such speeds. 

Interesting discussion (to me at least).  I just went
through a project where we had to develop a ball
bearing that withstood 1215F at 615 psia.  

An issue in performance engines and high speed
rotating machinery is the heat built up at bearing
surfaces from shear and contact stresses. At bearing
surfaces, I don't think you want the oil to stick to
the parts so much as you want it to flow and carry
heat away.  I had good success simply changing from 1
synthetic (MIL-L-7808) to another (MIL-L-23699) in a
piece of aircraft equipment (an air cycle machine, for
those who care).  After teardown we'd find no coking
(carbonizing of the oil to a near-diamond hard finish
that scratches rotating surfaces) on the bearings at
outer race temperatures in excess of 400F.  An issue
with motors is the oil that gets "trapped" and ends up
coking/cooking.  The real race car motors on this list
(of which mine is NOT) have modified crankshafts and
bottom ends to maximize oil flow.  Long time listers
may remember my buddy the Engine Nazi.  He had a
normally aspirated 700 hp 428 Ford motor in his
dragster.  The bottom end was highly modified to
maximize oil flow.  The clearances in the motor were
incredibly sloppy on purpose.  Where the normal
clearance between the edge of the connecting rods and
the ear of the crank were, say, .0015, he'd have them
open to .003 or .004 (piston to cylinder clearances
were also opened to 3 or 4 times their normal
clearances, primarily to provide running clearances
due to thermal growth). The bearings also had
additional channels in them to get the oil out.  He
used to say that the real drag motors were so loose
that the pistons were about to flop over on
themselves.  His motor would sound like a bucket of
bolts on startup with all the piston slap and bottom
end noise, but he got about twice the number of races
out of his motors than most (in drag racing, that
equate to like 3 or 4 races!).  He also felt the
biggest issue with bottom end integrity was rod bolts,
FWIW.  



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