Bored out 70-thousandths to 310 cubic inches and with a laundry list of modifications, this pushrod, naturally aspirated, 5.1-liter inline-six allegedly makes 625 horsepower.

The Ford 300 cubic inch straight-six is a staple of American truck culture, having literally helped build this nation as we know it. Found in Ford F-Series trucks in the 1960s all the way until ...