I've got a question regarding coolant temps I hope some of you can help with.
 We've been running the Eagle540 recently, getting ready for that impending
first flight.  Our installed instrumentation on the coolant side is located on
the higher pressure, high temp engine outlet side of the coolant circuit...
the flow comes out of the top rear of the engine to the thermostat housing.
 Temp sensor is installed in the t-stat housing.  From there it goes through
the firewall and down to the radiator, then returns back through the firewall
and on to the water pump.  The water pump forces the coolant into the block
and the circuit is complete.  We are not running 50/50 water/anti-freeze
because of the magnesium components... we are running straight Evans NPG.
 During recent runs (engine RPM about 2000RPM, the rev limiter is set at 3800,
so we're just over 50%) we're seeing the high temp side over 230 degrees.  NPG
doesn't boil until somewhere around 400, but we obviously don't have any
desire to operate at that kind of temperature.  For those of you who are
instrumented both before and after the radiator (evap cores, whatever) what
kind of temperature spread are you seeing?  I suspect I'll eventually be
instrumenting the cool side of the circuit, but would like to know what to
expect on the hot side.  If we're seeing a 40 degree delta across the radiator
(I imagine) is 250-260 considered too hot as a redline for the hot side?  (Our
oil temps are very well behaved, we still haven't exceeded 150 on the oil cool
side and TITs are running 1350-1400 at these reduced power levels... sounds ok
to me, but what do I know?)  TIA for any info you're willing to share.

     <Marv>

My before & after coolant temp delta was surprisingly low.  Only got readings at cruise power settings (6.5 - 7 GPH) where it was only 10 - 12 Deg F.  This could mean several things.  1.  Rads are no good.  2.  instrumentation was no good.  3.  water goes through system really fast.  

 

Or (4) it could be normal.  I don't think the answer is 1 or 2.  I don't have time to do calcs to see if 4 is the case.  Anybody got time to run them?  Assume GPH at 30 gpm if you do. 

 

Oil temp delta was higher (expected) at 20 - 50 depending on power setting.

 

Tracy