I just wanted to share some of the most scientific coolant testing that I am capable of. I have been chasing cooling issues for a while so I thought I would play with different restrictors, thermostat, and open system.

This is what I found:

Outside temp 75
Lower hose 137
Upper hose 98
Car holding at 186
Restrictor 3/4"

Outside temp 75
Lower hose 132
Upper hose 100
Car holding 196
Restrictor 1"

Outside temp 75
Lower hose 128
Upper hose 91
Car holding 188
180 thermostat

Outside temp 75
Lower hose 142
Upper hose 93
Car holding 197
Open system

Outside temp 75
Lower hose 131
Upper hose 92
Car holding 198
Restrictor 5/8"