How much horsepower on a 1999 5.3 vortec?

The horsepower of a 1999 5.3L Vortec engine varied slightly depending on the application (truck, SUV, etc.) and specific calibration. However, it generally ranged from 255 to 270 horsepower. You'll need to consult your vehicle's owner's manual or the engine's specifications label for the exact horsepower rating for your specific vehicle.