Wrap one slice of bacon around each ear. It probably won't cover the entire ear, but be sure it goes from one end to the other. Sprinkle with chili powder to taste.
Wrap the corn and bacon and chili powder in heavy aluminum foil and place over medium coals, or medium flame on gas grill.
Cook approximately 20-25 minutes. Time will depend on the size of the ears of corn, and how fresh they are.