so what are they doing using a load cell to see how much it pulls against the chain that u shaped piece is an electronic scale !i think it's pretty cool if it is actually hooked up .
If it works, it's pretty cool actually. Very redneck, but as a project it could be entertaining. If you could maintain a known load, then all you'd have to do is record the RPM of the driven wheels over time, and feed it to a computer. Calculating the horsepower would be easy. There's nothing magic about a dyno, the theory is simple, what costs is the implementation.