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