I thought a lower pitch prop provided more thrust at low airspeed (airspeed of the plane) because it moved more air at slow airspeed than a higher pitch prop. Thust is created by the action of accelerating air after all.

I thought high pitch props were not effective at low airframe airspeeds because the prop airfoil became ineffective due to the high angle of attac of the blade (stalled?). At higher airspeed the higher pitch prop starts to work better because the angle of attack decreases as airspeed increases.

So if the goal is to cool the engine on a test stand I would think you would want a low pitch prop.... or am I wrong?

edited for clarity.