[A26B]

Originally Posted by efnfast

It's my understanding that the bypass is not an open or closed loop, but rather modulates to allow some water through/around. I would think if all the coolant bypassed the rad, the motor would over heat at lightning speed, plus that design wouldn't make sense at all for just that reason.

That is correct.

Bypass volume is directly related to water pump output which is related to rpm.

Increase radiator flow & thermal transfer capacity +increasing thermostat flow capacity (holes in flange) will = reduced bypass volume & increased heat transfer.

Caveat: There is of course a lot more involved in centrifugal pump flow characteristics, fluid velocity, thermodynamics, etc. but within reason, the above holds true.