Maybe I’m ignorant for having this mindset, but I always thought you could go to a dyno to figure out how much power your car makes and that was the number you could proudly tape to your fridge. Jason Fenske of Engineering Explained has a different take.
Fenske dyno’ed his car, a canary yellow Honda S2000, and did four runs. While the horsepower stayed pretty consistent throughout the first three runs, the torque figures varied. This, Fenske reasoned was because the dyno didn’t pick up the car revving as high as it was, thus producing the sporadic torque numbers.
Which brought him to his final point: most dynos aren’t standardized. They are all calibrated slightly differently, so it’s very possible that you’d get two different power figures from two different dynos.
What dynos are good for, actually, is measuring the effects that modifications have on your car. If you have results from one dyno and then add, say, a supercharger, to your car, you’d see how much more power you’d be making because you’re measuring it against the same dyno.
It’s kind of like weighing yourself. The scale you have at home might not yield the same results as the one at the hotel. But at least with the scale at home, you use it consistently enough that you can track it if your weight goes up or down.