i only have it on a chevy small block and big block v8, but it is basically blocking the top hose, and bypassing from the top of the water pump into the engine side of the top hose. this is the closed loop that the motor circulates the water and doesnt let any flow through the rad until the thermostat opens, at that point the rad water is cool. i have seen as much as a 90 degree split, where the motor water is 180 and the rad is at 90, and it started at 100 for both. because the fan is pulling the air through the rad, it cools the rad water down, while the motor builds heat. and once the motor is up to the t stat temp, it cracks open and lets some of that cold water in, just enough to maintain the water, then closes and starts to super cool the water in the rad again.
Like i said it needs to be in a system that is made for it, and not a typical dead head t stat like most banshee or 2 strokes would have.