Loud engine knocking on 1992 Lexus ES300

I just bought a 92 lexus es 300, it has a very loud engine knock it sounds like it's coming from under the valve train, we took the cover off and cranked the engine by hand it didn't look like anything was wrong, the car has 239,000 miles on it, when you start the engine everything else is quiet except this knocking, and when you push the gas the knocking gets louder, I have not drove the car so not sure about anything else I want to get the knocking fixed first, we did a oil change, and replaced the oil filter, and air filter

Asked by for the 1992 Lexus ES300
Sounds like a Piston knock....if it gets louder as the revs go up.