Our closed loop coolant systems will have friction equavalant to some head
pressure, but if it is over 2 inches I'll eat my hat.

Eric;

Do you have a hat with a good flavor?  The pressure head equivalent of the
pressure drop around a cooling loop is much greater than 2", at cruise
conditions; well over 2 feet.  But d__n, right now I can't find the charts.
Bill; do you have data for your loop, or at least through the engine; that
you could re-post??

My Ron Davis Radiator (one of two in parallel in my system) has a pressure
drop of 2.25 psi at 20 gpm (roughly cruise condition); that's an equivalent
head of 4.9 feet.

Al