How do you get everything up to operating temperatures before you connect to the sled?
I would not want to pull with everything cold.

 

Mine usually doesn't take it very long to get warm again since I drive it there. I usually start it when the class before me begins. If you're worried you could try running the AC to put a little load on the engine to help build heat.

 

I usually bring the RPM's up to about 1500 when the class before me starts.