DaveLeonard wrote:

 After careful consideration, I think I am going to switch to Evans NPG (100%
 propylene glycol) during my annual this year when I flush the cooling
 system. Here is how I see it:

 Disadvantages:
 1. I will probably run a higher cooling temp, about 20-30deg higher best I
 can tell,  This will put my hottest temps up around 250F.  I think the
 coolant o-rings should be able to withstand that.  Otherwise, the increased
 temps will improve heat rejection and possibly BSFC without other negative
 impact.  Running higher coolant temps should also partially offset the
 decreased specific heat of the NPG (better temperature difference in the
 radiator).

Well,

there is a difference between an acceptable level of performance and getting
away with something. Distilled water is by a great margin the very best
coolant for IC engines. When you see any temperature on a gage, the metal in the
engine had to be higher that what you see on the gage because you cannot attain
100% transfer.
However you get closer with water than anything else. A 24 pound pressure cap
and 10% glycol should cover anything you would ever see in a high performance
rotary.

If you operate in cold areas 30/70 or 40/60 should cover everything. If its
cold outside boiling over is even less likely.

Propylene absorbs less heat and gives up less heat. Hoping higher coolant
temps will make the radiator work better is hopeful. The stuff needs to be hotter
to work as well as water. You don't want to see 250 with water in a rotary
let alone anything with poorer heat transfer ability. You need to be on the
ground looking at that high a coolant temp. Even 240 is way out of line.

Anything over 160 oil and 180 water costs HP. In a turbo engine the high oil
temps lead to detonation. The black puffs of smoke from the expensive V-8
indicate detonation.

Wonder why Evans has there own water pump?
If I remember correctly isn't this stuff flammable when its hot?

If you have to do this, stay above a quiet airport with long runways.

I have been racing rotaries since 1980, and have not lost one to cooling yet.

I have never used the Evans stuff, and never will. Even if it was free. It
dosn't make any sense to me.

Lynn E. Hanover

 
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