 LS2 BMW Swap cooling System Questions. (long)
06 GTO LS2 engine in the BMW and ready for plumbing. I am likely over thinking this so a little help/reassurance from the collective would be appreciated.
In the BMW, the radiator has a vent tube running to a pressurized expansion tank. This tank is where the 15lb radiator fill cap is and there is a 5/8” hose from the bottom of the tank that went to the return heater line. The heater line was always in flow as BMW used a bypass valve to isolate the core when no heat is called for.
I am not 100% sure of the LS2 coolant flow. Engine is out of a 06 GTO.
I am thinking I can tee the BMW radiator vent and LS2 head vent line together and run into the BMW overflow tank. Then route the 5/8 line from the bottom of the tank into the small heater port on the LS2 water pump and block off the large port.
Will the limited flow to the port be an issue for the LS? I am not running a heater in the car. I believe there is no flow when GTO heater is off but not sure. Am I correct that the smaller heater port on the LS pump is the return and that limited flow would not be an issue?
OR
Would it be better to block or loop the LS heater ports and run the BMW expansion tank return into the lower(?) radiator hose via a tee adaptor?
Finally, any issue with the tee idea for the LS2 heads to the BMW radiator into the Expansion tank. Understanding that the BMW expansion tank is under pressure. | 
