Fred,
Just got off the phone with my racing friend who refreshed my mind with
some points from our last year's conversation about using unpressurized,
neat propylene glycol as a coolant. First was that if you plan to do
this you want to be sure that every drop of water is gone from the
cooling system, for if there is any water present it will still form
steam pockets in the hot spots and negate the effect desired by
switching coolants.
He is familiar with the Evans coolant and says it is propylene glycol
with additives.
He also claims that one of the big advantages of running high coolant
temperatures is that engine wear drops significantly and is one of the
reasons all modern cars run higher temperature thermostats. However, as
coolant temperature goes up so does the propensity for detonation. One
way to get around this is to use "reverse cooling " where the coolant is
pumped from the radiator to the heads first rather than to the block
first. He says Moroso did an experiment with a small block Chevy engine
where they used propylene glycol with reverse cooling and were able to
run a 17:1 compression ratio without detonation! They attributed the
success to eliminating the steam pockets in the heads.
I think I'll go out to the garage tonight and switch the radiator hoses
around on my +4, take that lower rubber gasket off my radiator cap and
order some straight propylene glycol! An unpressurized cooling system
in an early Morgan should add years to the life of that Smith's heater
core, not to mention more heat from it in the winter 'cause you can now
run a 190+ thermostat.
Art Hart
Chester, NJ
'64 +4
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