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Dale , the problem with oil temps in the rotary is
that the oil might be able to stand considerably higher temps (particularly the
synthetic oil as you point out), but the engine suffers.
At least with the older and earlier 13B
blocks, overheating could and did cause damage at a temperature range
far below where you would have to worry about the oil decomposing. Overheating
apparently caused the seals to "chatter" against the housing as well as
reportedly "shrinkage" of the aluminum rotor housings. The guidelines were
a maximum of 210F after the oil cooler for the oil and 180F out of the engine
block for the coolant. Now, we have found that at least with the new
blocks the engines will apparently handle higher temps without adverse
effects. Apparently short excursions as high as 240F on the oil and
220-230F with the coolant can be tolerated without damage - but, the feeling is
that extended operations at those temps is risking damage.
The newer blocks seem to be considerably more
tolerant of somewhat higher temps reportedly due to changes in the castings, but
I and others have found to our dismay that exceeding that magic number (whatever
it may be) you do at risk. So that is why you will see more concern with
oil and coolant temps with the rotary at a lower temperature than would normally
cause concern with a reciprocating engine.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
Steve ... re: the above
underlined.
I would say that what you have is just fine
regarding your oil temp. Remember that the "delta T" between where you
are running and the temperature at where it quits working is quite high.
Especially if you are using synthetic oil. Molbil I keeps
lubricating quite well up past 400 degrees and beyond. Thus,
if you are running temps near 200 degrees you have near a 200 degree temp
spread (delta T) between what the oil can take away and what it IS taking away
in BTU's of heat dissipation in a stable system. That is a
pretty fat safety margin, when you figure you can run 100 degrees hotter than
what you are now and still have 100 degrees left before lubrication failure is
imminent. Obviously, lower is better.
Water cooling now is a
different story. operating coolant at temps near 200 while water
boils at 212 ... gives you a delta T of just 12 degrees to play
with. I know you can kick it up by anti-freeze, pressure on the
system, etc. etc. but the bottom line is that you have a lot
narrower delta T range to deal with, and you are always working the system a
lot closer to near it's maximum potential for heat dissipation.
Just a
thought,
Dale Smith
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