Many of you may have seen this episode of Mighty Car Mods which I'm a huge fan of, but this one caught me by surprise!

 

The intercooler when painted black certainly performed much better than when it was unpainted when there was no airflow. So, for people sitting a lot in traffic or waiting in line at a drag strip before their run, it is the way to go.

When airflow was applied, though, the difference was negligible. Indeed, with air flow, the unpainted intercooler showed about 3% better efficiency than the painted intercooler based on the numbers they presented (100 deg. temperature difference between input and output of I/C unpainted vs 97 deg. temperature difference when painted). Again, this is negligible, and may even be due to small changes in the test setup between tests, or may be due to some insulation effect of the paint. But if your intercooler is getting a decent amount of airflow from your radiator fans, I would not expect the black paint to make a huge difference.

In my case, my intercooler does not get much airflow from the radiator fans, so it could help me. Then again, I don't spend much time sitting in traffic and my car is setup for road course use, not 1/4 mile.