I'm here to tell you that's a bad idea.
Over
the years, there have been a few folks who have pushed for FIAT
replacement thermostats that open at lower temperatures. The factory
specified a 190-195 degree (Fahrenheit) open, but some aftermarket
producers have gone as low as 175 degrees.
What are the actual benefits of going lower?
Put your engineering hat on with me, and let's talk applied science. If you consider the
internal combustion engine as an air pump operated by thermal expansion,
*more* block heat is *more* power and efficiency. -- Every
joule of energy sent out to the atmosphere as heat
(through the radiator) is a joule of combustion energy lost. --
For proof-of-concept, look into
the experiments in the 80s and 90s with ceramic engine blocks. They ran
hot and achieved better efficiency (power), but nobody could make one
last for obvious reasons. The temperature limitation we have come to
expect of our motors is a function of the materials necessary (metals and gaskets) to build
long-lasting motors.
Modern
manufacturers regularly wait until 230 degrees (or so) before even
turning cooling fans on. Many run up around 260 before there's any
significant longevity concerns. That's mostly a function of superior
metallurgy and higher pressure cooling systems.
Running
motors cooler than designed (the FIAT DOHC included) is bad practice,
with almost exclusively negative consequences. It puts manufactured
clearances out-of-specification, because those specifications were set
*at design temperature* for component materials that expand at differing rates. Which means that engine components tend to wear
faster when too cold. Also, in more extreme cases, if engine oil is not allowed to
reach a normal temperature, the condensation that occurs inside a
crankcase (as a function of heat cycling) can create a significant
concentration of water. Obviously, this has numerous detrimental
effects.
Most people who swap in low temp thermostats do so because their cooling systems have other underlying issues. I would always recommend dealing with the problem over a potentially dangerous band-aid. You can see my post here on how to correctly burp the cooling system of a FIAT 124 Spider, to make sure you aren't chasing a simple problem.
Hope this is helpful,
Aaron
