Rob Burgoon

Hey guys,

Has anyone had any luck running less dexcool and more water to get temps down?

Does anyone have a chart showing dexcool concentration versus freezing point?

I am currently at 1/6 dexcool 5/6 water with water wetter. Car lives outside in San Diego. Should I add a little dexcool, or drain and switch to green "all makes and models" prestone?

rustyguns

unless you are in the mountains and the night temps get down to 25 or less for long period of time. you do not need anymore. i bet at that concentration your good to 10 degrees for an hour or so. i lived in san diego county in Poway for years and ran straight water with water wetter. no problems

the closer you get to 100 percent water with water wetter, the cooler you run..... a LOT cooler !!!!!!!!!!


then if you want the temp gauge stuck at 190 or less(whatever your thermostat is).. have your fans both come on early

DOCTOR J

FWIW:
As I remember the chemistry, Dexcool has the same main ingredient as the earlier versions
of Prestone - ethylene glycol. Thus its heat capacity and freeze-point should be almost
identical to the old liquids. The difference between the two is in the corrosion inhibitor
package, mainly.

Green Prestone used traces of heavy metal ions (Antimony and the like) to passivate internal
metal surfaces, and the inhibitors had to be renewed every ~2 yrs. Dexcool uses organic
'chelates' to accomplish the same task, supposedly good for ~5 yrs. The new 'all compound'
Prestone says it works with either kind of inhibibitor - but I don't know the details of how
that's done. Its main component is still glycol. Same for all the brands.

Switching between different colors of Prestone(or other brand names) only changes the
corrosion package you get. Any difference in heat transfer would mostly be due to the fouling
factor at the metal surface varying among inhibitors - probably a very small number (that
would be the 'U' in Q = UA delta T). JMHO

BTW, the one thing you CAN'T do is mix orange and green Prestone - those two inhibitors are
utterly incompatible.

Pure water has a higher heat capacity than glycol; but it seems to me it also has a little more
viscosity and weight to pump around.. HTH

Slalom4me

Some Dex-Cool product infoAs stated by DOCTOR J, Dex-Cool is an ethylene glycol type of coolant.
The main packagers of Dex-Cool specify no less than a 40/60 ratio
of Dex-Cool/distilled, providing freeze point protection (FPP) to
about -12ºF (-24.4ºC).

Note, it is not recommended that engines be run when EG/water
solutions are near the freeze point because the coolant tends to turn
to slush. To accomodate this, there are suggestions that a cushion
of at least 5ºF (3ºC) be provided between operating temperature and
freeze point. Based on that allowance, the min non-slush temp of a
40/60 glycol/water ratio becomes -7ºF (-21ºC).

For evaluation of mixtures outside the recommended range, there is
an FPP curve for ethylene glycol in the following chart.

FREEZING POINT of WATER/GLYCOL SOLUTIONS

Technical information about ethylene Glycol based water solutions

Rob Burgoon's mixture of 1/6th Dex-Cool to 5/6th water is equivalent
to an AF ratio of 17%. From the chart API chart above, this mixture
provides freeze point protection to +19ºF (-7ºC). If an allowance for
slush is made, the minimum operating temperature becomes +24ºF (-4ºC).

Something to take into account is that equipment inaccuracy and
operator errors made in the testing procedure of the glycol/water
ratio contributes to variations in the actual freeze protection. With
the exception of measuring fresh fluids into a new build, the ratio is
unlikely to be known with certainty. Considering the consequences
of a freeze-up as a result of a freak weather occurance or a trip to
another climate, 17% seems unnecessarily lean.

A refractometer company's write-up about refractometers, hydrometers
and test strips: Engine Coolant Testing.

FWIW, although glycol is less effective as a coolant than water,
glycol raises the boiling point of the coolant. At sea level, the BP of
a 50% glycol solution is 225ºF (107.2ºC), 12ºF higher than water.
With a 15 lb rad cap, BP of 50% glycol/water becomes 265ºF (129.4ºC).
Also, the additives help delay corrosion.

Regarding whether to add or switch, my vote is emphatically against
mixing or switching different coolants.

.

Falcon

Not on track. In 30 minute races, with water and Water Wetter only, and both fans running, these LS6's run 220-230* (coolant).

Rob Burgoon

Thanks for the info Slalom, I think I will come up to at least 30%.

Rob

fatbillybob

This is the track/autox forum. If you are on track do everyone a favor and stick to water and water wetter only. Use only antifreeze if you are on track and the overnight lows are below freezing. We have lost some engines at WSIR a couple years back as the morning temp started the day at 7 degrees. So think about the time of year you are on track.