[Squidward]

Both of my engines use a 180 standard Tstat. Both run a 4 core Champion. On my FB, I ran no tstat for a while to see how it would do. It never went above something like 157, and in the cooler months less than that. So I knew I had excess capacity. With my a/c on, it would bump up another 5-10 degrees.

[68 Firebird]

I agree with above posts. If the cooling system is optimized for the load, then
you will only see temp raise a few degrees over rating of stat. Trust me my
car was not optimized when I first got her on the road. Now she hangs within
a few degrees of stat rating even on hot days.
-running a hotter stat now and can tell she likes being a tad warmer.
-Severe Duty fan clutch, 2 row rad with one inch tubes, clearance WP and
8" crank pulley with 6.5" WP pulley.
-All baffles upper and lower are inplace, along with firewall seals
-trying a Motorad stat with a rating of one ninety two. Closest I could find
to a one ninety. so far she does not budge the gauge off one ninety.
-I will say it warms up and is snappier quicker then with the lower stats.

No answer is wrong here, just like oil and spark plugs. everyone will have a different
experience.

Gerry