Cooling Question

[Dynomite]

Today at 70 deg F Outside Air Temperature got same results as at 50 deg F Outside Air Temperature.

50 deg F - 70 deg F outside Air Temperature.
Ron Davis Radiator.
Haibeck Chip (fans ON 205 deg F, OFF 200 deg F).
1990 ZR-1 #72 (40,000 miles).
Stock Exhaust.
180 deg F Thermostat.
Green Antifreeze down to -10 deg F.

6th Gear
65 mph
1,500 rpm
207 deg F Engine Coolant Temperature

5th Gear
65 mph
2,200 rpm
190 deg F Engine Coolant Temperature

17 deg F cooler running 65 mph in 5th Gear rather than running 65 mph in 6th Gear.
Did the cycle several times with identical results. Coolant Temperatures moved from min to max and back in a minute or two after shifting Gears.

Idle at 850 rpm 203 deg F.

[XfireZ51]

Has the opportunity to try out new thermo both yesterday and today.
Yesterday, ambient driving temps started out at 48F and heated up to 56F by the time I ended the drive. In all driving situations, highway cruise, local street driving, driving under 65 and over 65 ( fan cutoff speed), the coolant temps
Varied between 85-89C.

Today, I got to drive in ambient temps of 73F. Again, in various driving situations. Hiway cruise, temps were practically glued at 86C. Idle would sit at 86C and climb a bit to 89/90. With fan turn on temps would begin to drop. Any increase in Speed would rapidly bring temps back down to 86C.
I changed calibrations to bring fans on later and drop out at a lower speed to make sure the fans were not assisting in the cooling.
With FAN 1 coming on at 88C for low speed driving (<12mph), temps circled 86-88C. High speed driving (>12 and past 55), temps were in the 86-88C range. So just air moving thru the rad is enough to maintain a very stable temp. Driving at 100mph raised temps +1.
Overall, I'd say I am pretty satisfied. The thermo w 2 bypass holes appears to keep enough heat in the motor w cool ambient temps. We'll see what happens next year w 80F+ weather, but so far it looks good.

[XfireZ51]

Quick update. Sunny New Years Day. 35F outside so took opportunity to roll the tires and basically heat the car up a bit. I was curious how the thermostat would work with now 2 bypass holes rather than 4. This is a stock thermo.
At cruising speeds 55-70mph, coolant temps stayed at ~ 185F/85C. Unlike before, driving around in 35F weather would have caused the coolant temps to drop down to 150 or so.
So overall, the combination of a Fluidyne rad w stock thermo (w 2 bypass holes) seems to have given the result I was looking for.