I am gratified to see spirited discussion on this topic of concern to all
of us.
Mike: the PFA decision was to abruptly ban the use of Evans because it is
flammable.
Ron: Clearly you had fun playing with flammable liquids, but nothing in
your data adds to critical decision making here.
Gilles: Your comments about heat of vaporization may or may not apply. It
depends totally on the dynamics, by which I mean
the rate of nuclei formation. Dean and the Rotax engineers seem to be of
the opinion based on their teardowns of damaged
engines that stable nuclei do in fact block heat transfer. The proof
would be to place a fiberoptic endoscope in a coolant channel
during typical conditions and see the phenomena, along with placing micro
-thermocouples in well points milled into the block
next to the channels and in the fluid inside the flow channels. This of
course ignores secondary effects like the conversion to
turbulent flow due to nucleation and the consequent drop in flow rate ;-)
(God, I loved my course in fluid dynamics 30 years ago)
In the mean time, the current best practice per the Lockwood/Vogel
organization with the tacit approval of the Kodiak group is:
Use 50/50 with the 1.2 bar cap.
NB: The day after SnF, I put in the new 1.2 cap ($29. at CPS, $74 at
Lockwood at SnF, since reduced). During the next taxi run to
the active, all the coolant blew out my overflow tank. Fortunately it has
not happened since
Ira N224XS
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