X-Mozilla-Keys:                                                                                 
Fred wrote:

According to Evans data, the thermal conductivity and specific heat of
propylene glycol is lower than water plus ethylene glycol while the viscosity
is higher.  Basic heat transfer laws suggest that the heat transfer
coefficients must be lower.  Only claim to fame is higher boiling point.

I believe the arguments about film boiling are bogus because water and water
plus EG have extremely high nucleate boiling film coefficients unless the
temperature difference between surface and liquid is very high.  My opinion:
good marketing, bad science.

Fred Moreno

Thanks Fred. I think we discovered all that when we had that long 
discussion on this subject a while back. Our conclusions were
NPG is not worth the risk in a rotary.

BTW Jim Mederer (Racing Beat) and I discussed the rotor housing
shrinkage problem when the engine is overheated. He brought up
a point that I don't think we have discussed so far on this
subject. Jim says; "Why bother with necked down tension bolts or
bellville springs under the tension bolt heads? If the engine
over heats the rotor housings are trash anyway because the 
heat treatment goes away. Simple solution. DON'T LET YOUR
ENGINE OVERHEAT!" Easy for him to say :-)
 
Paul Lamar
 
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