Quote:
Originally Posted by Eldi Z
...And another piece of important detail picked up from your dyno. This was a DynaPack, meaning, that the measurement was right at the Hubs and this means the most conservative numbers possible - lowest parasitic losses.
Guess that a Mustang dyno would tipically show ~ +3-5% higher readings than a DynaPack (like you measured on) and a DynoJet would show the highest numbers overall with ~ +10-12% compared to DynaPack. Makes sense?
|
I hear ya. I just think its a bit more nuanced than that. Plus, I think you will start a huge flame war with the dyno accuracies
Everybody and their brother has had an opinion on this subject since the first dyno was created.
In the GM dyno wings, we calibrated (and I'm sure they continue to) our dyno cells with 'gold standard' instruments that were traceable to NIST. Even then, the accuracy and repeatabilty were generally ~1% of the standards(s) - full scale in some cases, % reading in others. However this could vary depending on the range of the unit. I mention this because I suspect most dyno's out there are likely NOT calibrated at a reasonable frequency. Calibration drift is a very real thing, for many reasons. Moreover, with all the variants out there (eddy current, intertia, hydraulic) you will have error between them, as you mentioned.
Add in the mix, wheel size/weight/traction, dyno operator setup and configuration, ambient conditions (let's not forget calibration and accuracy of the dyno's ambient sensors), and probably a few other variables I'm leaving out - you have a healthy scenarion for varation in output. Quite frankly, It's impressive that the dyno manufacturers have things as close as they do. It just means they've done the best they can to eliminate humans from the equation as much as
reasonably possible.
At the end of the day it comes down to drivability, seat of the pants feel and track times (if that's your thing). Big numbers are easy to acheive - it just takes money and a sliver of knowhow. Drivability tuning,imho, is where the hard work is and what matters the most on a street car.
Anyways, sorry for the rant
