All of the weather variables aren't really a problem with the dyno. Those are variables that are actually affecting engine output. The fact that different runs will produce different values are because the engine is producing different power. I would tend to believe them that the dyno will consistently measure to within .3%, but good luck getting your motor to be as consistent. The end result is the same, you won't get usable data across days or dynos, but dont necessarily blame the dyno for that.

 

Good point.

 

More so then ET at the track, MPH is more telling when it comes to power