What weight are those arrows that you are using, my heaviest arrows are wooden shafts coming in at 452.2 grains and they leave my bow at 151 ft/s which I work out as 9.75ft.lb/s, my lightest are carbons at 327.2 grains and they leave the bow at 170 ft/s or 7.95 ft.lb/s, that is nearly 116 mph.
I assume you are using a
compound bow to get a much higher speed but even that must be around 300ft/s so those must be heavy arrows.
What I find interesting is that the heavier arrows absorb more energy from the bow than the lighter arrows, one experiment I would like to do is find the optimum arrow weight to use with the bow to get the maximum energy transfer.
[Speeds measured on a Caldwell Chronograph].