What is the horsepower of a ford L6 engine?

There's no single horsepower rating for a Ford L6 engine. Ford produced inline-six engines for decades, across many different models and years, with widely varying displacements and power outputs. The horsepower varied greatly depending on the specific application and year. You'd need to specify the *exact* engine code (often found on an engine block) or at least the year, model, and displacement (e.g., 170 cubic inch, 200 cubic inch, 240 cubic inch, etc.) to get a precise horsepower figure.