by Steve Jack
A few of you good folks must have spotted other articles that I have done either in print or online about this subject.
At the request of a few folks here I am putting this up
for what it's worth and expanding some information about this as well.
The argument is about running 160 degree thermostats and the good and/or bad results. Now keep in mind that thermostats have absolutely NO effect
on your systems ability to cool, simply a regulator of the range it operates in. So, if you think a 160 will cure an engine running at 220
with a 180 thermostat...forgetaboutit! This is not about cooling capacity at all.
The graph to follow illustrates
the importance of how critical optimum coolant temperature is to the longevity and performance your engine. Cooler water makes horsepower and
warmer water minimizes engine cylinder and bearing wear...or so it's thought, but only to their own limits and ranges.
There is a range where
both optimum performance as well as minimal wear share similar characteristics. That number lies in the 175-180 degree
range as shown by the overlap in the chart which correspondingly requires a 180 degree thermostat. FWIW, higher
operating temperatures of today's engines are to fight combustion by-products and pollution. Also, engine oils are designed to work over a
specific temperature range with optimum performance starting at temperatures that require the coolant to be the very
same 175ish range. And don't forget the moisture issue. Have you ever seen water vapor coming from your tailpipes? Sure..and the very same
thing happens INSIDE your engine. YOur engine forms moisture inside when it cools and condensates on the walls of
the inside. This moisture the is washed down into the oil when started and then awaits vaporization by internal temperatures rising enough
to bring the moisture to the appropriate corrected vapor point (boiling). If enough moisture is left behind it
combines with combustion byproducts to form acids that become dissolved in the oil itself. The oil becomes more acidic as the age of the oil
progresses and picks on certain parts eventually. Also moisture will corrode other surfaces. So, it's important
to get these engines to a satisfying operating temperature as soon as possible. Usually oil pooling temps are about 30 to 40 degrees higher than
the coolant temps. This is a generalised statement and can vary with load and engine design but you can see why
you want your oil over 212 degrees to boil out the moiture immediately! A 160 thermostat usually does NOT accomplish this temperature.
Years of research show use of 160 degree thermostats is way too low to be considered for performance or engine
longevity. As the chart above illustrates, engine wear increased by DOUBLE at 160, than at 185 degrees. The 160's were invented for and commonly
used in older, open loop cooling systems where only 6 pound radiator caps were used, and low 212 degree boiling
points were the limit. We know better now.
Many early hot rodders found the 160's to be a smiggin better performing than the 190's, however the
in between 180 appears to satisfy both ends of the spectrum. The correct water temperature and thus resulting
metal operating temperatures required for the cylinders to achieve a minimum specific temperature in order to allow a fully mixed Air/Fuel charge
to combust efficiently is a minimum of 180 degrees coincidentally. If you use 160s be aware that this can have a
degrading effect over a time on your engine. I know alot of rodders still using them however to whatever ends they want...and that's okay.
Heck, I know guys that run NO thermostat and most of you know that's another book to be covered. I just report
what I learn...and you decide what's best for you. I hope this satisfies you information junkies out there.
Steve Jack
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