Thanks to Murry, it seems a whole new set of cool possibilities
has   arisen for warming up our Wankels.

   It's been a long time since I worked on diesel trucks, so I was'nt
  aware
   of Evans coolants. I just read through a couple long threads on
an RX   forum debating the issue. For more than a year now I have
read this   forum and have not heard of this stuff. If it's true the
pressure   remains low, or even zero, then we should be chasing this
one down in a   hurry. I have used water wetter for a long time in
my porsches and MX   bikes. According to what I have read so far, I
would have saved myself,   and a lot of other people, many headaches
by using Evans coolant   products.

   So what is it? Are the diesel guys wrong, and are the few RX
  enthusiasts
   similarly deluded, by promoting Evans products? Obviously, there
are a   lot of advantages in using a coolant that does not vaporize
within the   passages at or near zero psi; and what sort of pressure
will we see if   we use it in our pressurized systems? If it does'nt
vaporize, or   vaporizes very little, then we have a winner don't we?

   The stuff's not that expensive. Who wants to be the first to try?

   Search for Evans NPG+, on ebay.

   Anyone have a good set of specs on this stuff?

   Ed Carver

   I know people have used it but someone mentioned the heat transfer
   coefficient between coolant and metal is lower than ethylene
glycol.
   Evans coolant is mostly propylene glycol.
   In order to properly test it one must have a "cylinder" head temp
   sensor.

   Paul Lamar

  We had many long discussions about it a few years back.  I have
tried
  it.  I was using it when I lost all my coolant and landed on a
road in  2006.  You cannot run zero PSI.  All of mine squirted out
past a 7 PSI  cap and that is why I landed on the road.  It is used
in diesel engines  to raise the temp without boiling the coolant.
But we don't need or  want our temps as high as the boiling temp of
regular 50/50 coolant.  At  a given temperature, Evans will not
remove the heat as well as regular  coolant.

  No benefit to our application.

  --
  David Leonard

  I guess that means the stuff expanded when it got hot and that was
the  end of it. I was wondering about that while reading on the RX
forums as  some of the guys ran it at zero psi and never had a leak.
Some of them  used 13psi caps, I guess it just expanded and went
into the catch can to  be drawn back when it cooled off. I'll sort
out the expansion issue.

  It appears a radiator size increase is required in many
applications,  cars or trucks.

  Seems to me a big advantage to Evans would be the coolant would
not boil  around the spark plugs.

  Ed Carver

  -- -----------------------------------------

  Dave nailed it on the head. To summarize:

  1. The heat transfer from metal surfaces to the coolant is not as
good as a  Eth-Glycol  coolant. This is because of three factors,
 lower heat capacity,  higher viscosity, and lower thermal
conductivity (all moved in the wrong  direction)
    a. In terms of heat transfer 'goodness' , water  50-50 Eth
glycol  Evans coolant.
    b. To compensate for the poorer thermal transfer properties of
the Evans  coolant, a system has to either run hotter (greater delta-
T) or have  increased heat transfer area (bigger radiators)
    c. The viscosity of the Evans coolant at low temperatures is
pretty
  high, and the pump may not circulate it adequately until it is
warmed up.  Could be a problem in the winter, and may have affected
Dave Leonards  incident.

  2. The 'advantage' of Evans coolant is the lower vapor pressure
when at  operating temperature.

  3. If I recall, Dave's incident happened after he switched from a
water mix  to Evans, then flew to Mammoth and it cold soaked
overnight before taking  off.  IF he didn't get ALL the water out of
the system, and the high  viscosity of the coolant kept circulation
through the heat exchangers slow,  THEN the temperature in the
engine could rise to where the residual water  would generate
pressure, flash to steam, and blow the coolant out of the  system,
even though the temps in the rads was low.

  4. Diesel trucks like Evans coolant, but they can run at an
elevated  temperature, whereas with the rotary we are limited
because of the O-rings.

  I have a whole presentation that Evans Coolant made to Argonne
National
  Laboratory  a number of years ago that shows the need for
increased coolant  temperature, etc. Looking at those charts made it
clear to me that it was  NOT appropriate for aircraft use with a
Rotary engine.

  Bill Schertz
  KIS Cruiser #4045
  N343BS
  Phase one testing Completed

Paul,

Whats the best stuff to use to flush the coolant system? I've heard
of CLR, TSP
(tried both), that stuff u can get @ auto part stores in the lil
yellow jugs, vinegar...and a 2-part system that is no longer
available, but apparently worked really well (go figure).

I'm lookn for something that would be strong enough to flush the
crude out of the heater core too..

Thanks -Dan

If you have a very dirty system, a few oz's of muriactic acid mixed to
dilute and then top up cooling system.  Run for about 15 minutes.  Drain
and flush with water from the garden hose.  Pull the small hose, the cooler
one, return to the engine and back flush the heater core.  If you can
remove the pipe plugs from the block to fully drain it is good.  Refill
with new coolant and distilled water.  Distilled does not have the minerals
in it that drop out and plug the cooling system.  A pressure test is a good
idea to find out if you have any corroded welch plugs with pin holes in
them.

Dale Davies

Engines are designed to run hotter today than they did in the days
before emissions raised their ugly collective heads.
jd