Mark, Mark, Mark,
Torque alone doesn't make anything go! Torque is a measurement of force only and is but one component required to motivate something. To actually move something, we need to do "work" which is defined as force x distance. And doing that "work" in a finite amount of time requires "power" which is amount of work performed in specific amount of time or work/time. For example, a car's brake can apply force or "torque" to the wheel(s) of a car parked on a hill to keep it from rolling, but it certainly can apply torque while rotating the wheel (work) and it definitely can't rotate the wheel very fast...
Let's try a little though experiment:
Imagine a person with a long torque wrench, say like this 3/4" drive 600 ft-lb model
Torque Wrench
With this torque wrench, we can apply up to 600 ft-lbs of torque to something...maybe even a prop hub. How much torque did you say that IO-550-N makes at 2700 RPM and 310 HP?*
OK, so said person (or people) can use that wrench to apply torque to our airplane's prop hub, but to make the plane move we actually have to turn that prop, i.e. do work on it. Of course, even though our torque wrench person is capable of applying a lot of torque with that torque wrench, he's probably going to get tired after trying to turn our propeller more than a few revolutions (doing all that "work") but more importantly, he probably can't turn it very fast while applying all that torque, certainly not 2700 RPM. I.E. he can't make much power.
So you see, torque is not what makes airplanes go!
*So the IO-550-N making 310 hp at 2700 RPM is producing 603 ft-lbs of torque. How much power do we get with 603 ft-lbs of torque at only 2000 RPM? About 230. Is the plane going to go as fast with that same torque at 2000 RPM? Thus, as I said, it's actually power that makes our airplanes go fast.
Skylor
p.s. Horsepower = Torque*RPM/5252. Torque is our measurement of force, "revolution" is our measurement of distance (work) and "per minute" is our "over time". Power = work over time (work/time). The 5252 is simply a unit conversion factor of 550*60/Pi. Part of the reason that it's believed that "torque" is what makes things go is because aircraft engine output figures are very often compared at the same RPM (2700) and thus the torque values of engines of different power are directly comparable...but torque without a measurement of speed (RPM) does not tell us anything about the capability of an engine and how fast it can make an airplane go.