Jeff Spitzer wrote:

Paul wrote:

Chuck_Harbert@arkwright.com wrote:

snip

I've been talking with Griffin radiator, as well as Evans NPG

(non-aqueous

propylene glycol) (Dave Wright) about what would work best. What I've

found

out could fill a book. NPG systems are a whole different set of
circumstances. You took their ad with you and you might remember that

they

said "down sized radiator (less frontal area)", but I only just found out
how that is accomplished.  If pure water is 1.0, then 50/50 h20/ethylene
glycol is .8 for heat transfer, and NPG is .7. However, water will only
absorb about 9,300 btus/lb, whereas NPG will do 15,500 btu/lb. Thus, to
reduce rad size you must increase the flow rate for an NPG system. You do
that by eliminating or reducing the size of the thermostat and increasing
the pump speed. Modern cooling system design makes the choke point the
thermostat which ensures higher pressures in the cylinder head area which
is critical to avoid hot spots. They say that a 260 degF NPG temp has the
same cooling characteristics as a 220 degF water/glycol for hot
spots/detonation.

snip

Chuck, be carefull and don't run that stock water pump too fast.
Check with Racing Beat on that subject. I think the stock pump is
limited to 7200 RPM but that is from memory. Jim M dug up a sprint
car engine water pump someplace for his turbo three rotors but I have
yet to locate the source.

BTW what is the configuration for a Griffen "three pass"?
Is that down in back up in the center and down in the front?
Or what?

Paul Lamar

That speed limit is based on cavitation.  A pure PG system (NPG) will have
greater cavitation resistance all else being equal.  The problem with NPG
systems (there can be no patent or rights for running pure propylene glycol
as a system...whoever claims to be defending such is nuts) is that they
cannot be used the same as EGW systems.  I should know, I designed a custom
NPG system for the Moller rotary.  The key is to run the system very hot.
The engine must be properly designed for this or you will not get an
advantage from NPG.  Please, I beg of you, don't get sold on some false
improvement from NPG for an auto conversion.  It doesn't exist.  Use the
EGW mixture the engine was designed for or pay later in overheated
components.

Jeff Spitzer

 
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