RTicUL8 said:
I plugged the overflow tank fitting (the stock bottle did not send to an overflow tank, and neither should this one).
Sorry, I have to call SPOBI on this one. Since I believe I was the first person in
to do this conversion, I think I understand how it works.
The plastic bottle is filled only halfway, so as system pressure builds up the air in the top of the bottle simply compresses. That's why you don't have an overflow/recovery bottle. (That also may explain why some people keep blowing caps -- the bottle is supposed to be filled to the top of the little post inside, which is about half full. If you fill the bottle to the top, there's no room for the coolant to expand.)
The Moroso tank with a radiator cap essentially changes you from a "closed" (sealed) system to an open system. Sure, you
can plug the outlet that's intended for an overflow bottle. But then you have to be sure to only fill the Moroso tank halfway so the system has some space for expansion. This leaves air in the system.
It's much better to put a barb fitting in that hole and run a tube to a catch/recovery bottle. Then you can fill the tank all the way to the top and have a cooling system with no air in it. As the cooland heats up and expands, the excess goes into the overflow bottle, and as the system cools down the excess is then drawn back into the system.
If you install the Moroso tank with an overflow/recovery bottle, you basically convert from a closed to an open system while still retaining the original sensors, etc.