Dave,
Thanks for the info-
I have run both the 4 lbs cap and the 0 lbs cap on the truck pre expansion tank.
With the 4 lbs cap I do not loose coolant- I just like the 0 lbs cap because that is what came on it.
and the expansion tank lets me tinker-
I think with the 0 lbs cap open to atmosphere it causes coolant to evaporate and the positive pressure in the radiator blows the vapor out of the vent tube where it does not return to the radiator.
What I want to see(mainly for purpose of running the 0lbs cap) is if the expansion tank will stop the loss with the 0 lbs cap.
I think it will because by the time the vapor flows through the hose to the expansion tank it has had time to cool, plus the sudden volume orifice change from the small hose(roughly 5/16" ID) to the large cannister cause it to condense.
That way it is not being lost but being allowed to breath and then when the radiator cools the change in pressure in the tank will draw the coolant back into the tank.
I told you I have no life, so fun experimenting like this helps me pass the time, and figure out why they thought of offering the tank in the first place.
The 7lbs cap would be nice for the higher boiling point.
Nice engine by the way- I bet that thing is a rocket.
