I have an r53 dedicated for track. I deleted the heating system and oil/coolant system and installed the oil/air intercooler. Also installed an aluminum overflow tank but am have over heating problems relatively quickly once driving. 3-5( minutes) what advice do you have for cooling system routing using that setup? Anything special ?

 

What did you do to delete the heater core and oil cooler? I would be tempted to believe that you crossed a hose, or pinched a hose, and now your cooling flow has been compromised. Or, an even simpler case of having air still in the system…

 

You loop the core lines to each other.
Also, if you have a vacuum bleeder, use it.

Finally: reinstall the heater core. This is basically another radiator for your coolant system, allows for more capacity and ability to remove heat from the cooling system.