A deep steady hammering that speeds up with the engine. Worn bearings until proven otherwise.
Worn rod or main bearings, low oil, or oil starvation. Sometimes bad fuel pinging under load.
Stop driving. Check the oil level first. A knock that rises with load is a tow, not a drive.
Reading about sounds only goes so far. The tuner on our home page listens in your browser and tells you what it hears. The app goes further: it names the exact fault, checks it against your vehicle, and tells you how urgent it is.