extracted from my corral project.
fastest horse speed i have gotten out of this device and sensor distance so far, without potions is 17 arrows.
(player sprinting speed is 40 arrows across it for reference)
sensor to sensor measures 89 blocks.

if someone needs a world save rather than a schematic, just build the device using the picture in your own world and extend the other sensor out to whatever distance suits you. it won't take you longer than a few minutes.