Mike McGee wrote:

Continuation of topics from a tech Q&A session at Pineapple Racing in
Portland, Oregon on Feb 22nd.  This is the last one, I hope the posts

have

been at the least interesting and maybe we learned something.

This is a topic that has also generated traffic on the list in the
past.  Most people will use the ethylene glycol & water at somewhere
between 20/80 and 50/50 mixture.  The guys at Pineapple Racing are

pretty

opined that the best coolant to use is the Evans Cooling NPG+.  Of

course,

they also sell the stuff.

Looking deeper into this, when Pineapple Racing sends a street rod or
racing engine out the door it has Evans NPG+ in it.  I seem to remember
(don't quote me on this) that if you have one of their engines your
warranty depends on using NPG+.  Their web sight has a good write up on

the

stuff with some interesting points.  Primarily for us airplane folk, the
claim is you can run it with an un-pressurized system.  Without
regurgitating everything here, I'll point you to the web site.
http://www.pineappleracing.com/Prod-EvansNPG.html

The down side to Evans NPG+ is the price.  Without calling around, the
first price I found on the net was $89/4 gallon case.
http://www.dieselsitetoo.com/product.asp?0=207&1=220&3=42
You DO NOT cut this with water, it runs straight, so you use at least

twice

as much.  In fact according to Pineapple you need to flush with Siera
(propylene glycol) in order to absorb all the water after flushing out

the

EG if you're switching over.  At over a hundred bucks, an expensive
installation.

Everything is a sales pitch until you have tried it or seen it work.

The

guys at Pineapple Racing have enough credibility with me that I will
probably try it on the test stand and move it to the plane if
successful.  The benefit of having an atmospheric pressure cooling

system

goes without saying..if it works at half an atmosphere (18,000 feet).

I'll

be studying this some more.
http://www.evanscooling.com/

Comments?

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode

Without having a thermal couple located within 2 mm of the combustion
chamber adjacent to the lower spark plug (cyl head temp gage) I can not
say if NPG (propylene glycol) works or not. There are some theoretical
heat transfer problems with it as I recall.

We had a long discussion about it on here a few years ago. It may not
boil over but that does not necessarily mean it is cooling the metal
like it should.

Paul Lamar

Paul,
Evans Coolant is pure Propylene Glycol. It may work fine if you can take
higher metal temperatures, or if you have a bigger radiator (i.e. in a
truck).  The problem is the heat capacity is lower than Glycol/water mixes,
the thermal conductivity is lower, and the viscosity is higher.  All three
variables just moved the wrong way.

In an engine that can be run hotter, it might be okay, but with the seal
temp problems on the rotary, plus the marginal radiator capacity that can be
squeezed into the cowling, I think you are asking for trouble.
Bill Schertz

 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2002 All world wide rights reserved.