* Year of manufacture: Engine designs and technologies improve over time, leading to variations in horsepower.
* Vehicle application: The same engine might be tuned differently for different vehicles (e.g., a truck versus an SUV).
* Modifications: Aftermarket modifications can significantly increase or decrease horsepower.
A 5.3L engine might produce anywhere from around 280 horsepower to over 400 horsepower depending on these factors. To find the horsepower for a *specific* 5.3L engine, you need to know the year, make, model, and trim level of the vehicle it's in. You can usually find this information in the vehicle's owner's manual or online resources like the manufacturer's website.