I discovered an article on the Kalmbach web site that ostensibly lists the Baldwin-calculated DBH curves from several 4-8-4's including the Frisco's 4500 class. Based on the plotted curve, the 4500's produced a maximum horsepower of about 4200 HP, which is considerablly less than the 5600 HP listed by Stagner, who cites the Frisco as his source. http://ctr.trains.com/~/media/Files/PDF/4-8-4 Locomotives/5-Later Baldwin 4-8-4 DBHP.pdf http://ctr.trains.com/en/Railroad R...ted drawbar horsepower curves for 4-8-4s.aspx
That's interesting, because David P Morgan is his Book "Steam's Finest Hour" lists the 4500s max HP at 5600 between 47 and 65 mph.