Re: Bob Myers input requested, RE: more heat!

[James Marriott <marriott@pophost.micron.net>]

>Sorry, I have no specific data at hand.  In general the statements above
>are correct.  Most materials have a lower heat capacity (specific heat,
>cal/gram-degree) than water.  Therefore a coolant higher in water content
>(high specific heat) should be capable of absorbing more heat than a
>coolant high in ethylene glycol (lower specific heat).

Mr Myers, tsk tsk! Cp is given as per mass, yet the system holds per
volume! ;-) I've been down this road trying to boost the meager output of
the 4kq (including a custom 0.5 ohm resistive heater installed in the white
plastic plenum. It STILL SUCKS.). On a volume basis, EG only carries about
54% the energy of H2O. The moral:  use _just enough_ EG to keep the system
from freezing at your lowest expected temp if you want max heater
performance in the winter and max radiator performance in the summer. Of
course, there's the corrosion factor to deal with. Draw your own
conclusions and make your best guess.

FWIW, the 200q runs PG Evans, and the 4kq 50/50 EG/H2O (PG in the spring,
$$ permitting). Boise's record low is -26 dF.

BTW, the only liquid I know of with a higher Cp than water (~4200 J/kg*K)
is ammonia (~4800 J/kg*K).

>Lowered freezing point of the coolant will probably pass through a minimum.
>Coolant either more or less concentrated than this particular mixture is
>likely to freeze at a higher temperature.  Exactly what the composition of
>this specific mixture is unknown to me.  (Perhaps the 70:30 ethylene
>glycol:water mixture?)

Superb guess. 70 EG, 30 H2O gives both lowest freezing and highest boiling.

hth, keep warm/cool as needed, happy new year, and

cu
James
'87 4kq (alias "late-B2 90q")
'89 200q (K26, torsen, aero handles, no bag)
'86 4ks, lives on in memory
http://netnow.micron.net/~marriott
Boise, ID, USA