Originally posted by mgmshar
That's a good question. The only data I have is "hand-touch" data. Basically, it goes like this. When I had coolant going through the TB, I would not be able to touch the TB after driving the car around the street for a short period of time. After I blocked off the coolant, I could touch the throttle body without burning my hand. That's not exactly scientific, but that's my experience.
Remember, the reason GM put that feature in the throttle bodies was to improve start-up emissions by HEATING the incoming air, and to prevent icing of the throttle body by HEATING it. Cooling the throttle body was not the issue. However, it would be really interesting to get actual temperature data under "scientifically controlled conditions".