Upon reaching the end of the runway, my water temps were around
   120
   degrees instead of the normal 160 to 170.  Temps during climb rose
   slower. Upon reaching 7000 feet, my water temps were back up around 195
   and oil temps were up to 190, Somewhat disappointing.

It might be somewhat instructive to know that one of the absolute
"no-no's" of early Mazda rotaries was to NEVER give it heavy
throttle/high rpms until the coolant temps were up to normal
temperatures (180??).  The issue was the differential expansion
coefficients of the iron and aluminum in various components of the
system causing differential movement and the seals being unable to deal
with these rapid movements resulting in water and oil mixing...NOT
GOOD!  Whether it is still true with the new seals/materials I do not
know.  My '88 RX7 has 130,000 miles runs like new and gets it tail
twisted regularly....but never until the coolant temp hits the
normal/thermostat open range.

120 deg at WOT pouring 200 HP worth of heat into the system seems asking
for trouble to me??  Also while everyone seems afraid of 210-220 degs
continous, my experience says that this should not be a problem
releative to durability and in fact many OEMs purposely run engines in
this range to maximize fuel efficiency.  It is also true that the
lubricity and temperature stability of commercially available oils in
2005 are superior to those available in 1985.  215 deg F engine coolant
out to radiator temperature _might_ be detrimental to total maximum
power output, but should improve fuel efficiency....especially if the
engine inlet air is not heated in the process.

Don't discount that "racers" even including NASCAR are never continously
at WOT and thus experience some pretty severe temperature excursions and
their "220 deg F" might actually be excursions between "250 deg and 190
deg" shown as 220 on the gauge due to lag in the gauge response.  The
temperatures cannot be very stable in any case due to the tremendous
variation in rpm and resulting coolant flow combined with rapid changes
in HP output.  It is in fact quite likely that the system temperatures
could well "resonate" if the heat input was out of phase with the
coolant flow, ie...just as the thermal flow hits the metal:coolant
interface the WOT comes off and the rpm goes down reducing BTU pickup
from the now slower coolant flow....then vice versa.

On this score, our constant HP output conditions are much easier to cool
than "racers" and the temperature readings we achieve are probably quite
close to the second to second conditions being experienced in the
system, except possibly for nucleate boiling in the immediate vicinity
of the spark plugs at the very limit of acceptable operating limits.

What is not to like about 195 deg coolant and 205 deg oil?????????

Doug in CO

My only comment Doug was this was only a 80 degree F day. What happens
when you have a 100 degree F day? The rate of heat transfer goes down
20%.


Paul Lamar

The Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
Copyright 1998-2005 All world wide rights reserved.