Pulley Diameters

I had a Farmall tractor that I ran 24-7 for 3 weeks at the time powering paddlewheel airator in catfish ponds that didn't even have a water pump on it and while working in stationary position didn't run hot!
was more than likely a 4 cyl., that didn`t make over 36 h.p. too !
IF THAT !