We can agree to disagree.
PS my car makes 500 smith whp.
skeet. skeet. skeet.
I believe I said all three could be wrong, but 2 or more can’t be right with different readings.
WINNER!
Sure they are all attempting to display hp/tq, but they all use different measuring devices, AND their software / calculations are written differently. Of course you will have variation.
Its not like these dyno’s are manual units with a fucking dial displaying HP. They are digital, calculated numbers based on the force/resistance/whatever the dyno is measuring at the rollers. Since they all use different methods to record the force, there IS no standard, even though the unit you are seeking is a standard…that’s the miscommunication between newman and smith…
anyway, every1 knows mustang dynos read lower by a lot, they are notorious for it. So if ur gonna be using it, baseline on the mustang, and continue tuning there, and it wont be a problem. if you are looking for big numbers, hit up a dynapack or dynojet lol.
until a coast down procedure is performed on each vehicle the numbers resulting from one dyno are absolutely useless in regards to comparing them to another dyno. like someone mentioned, if you continue to use that same dyno to make calibration adjustments and such, then youre good to go! just dont get pissed when your car “makes” 20% less power than another dyno, because it means absolutely nothing.
the problem is the parasitics of each particular car and each particular dyno skew the numbers. the coast down procedure tares out both leaving you with consistent data.
just because the STMs dyno outputs lower numbers than another, doesnt make it worse or less accurate. hydraulic dynapacks for example have less control than electrostatic type dynamometers, so STMs dyno is almost certainly more accurate than most other dynos.
What if each dyno is reading the unit value of horsepower (the equation that Newman gave us) acurately, but that number is actually changing due to the way the dyno loads the motor? For example, the mustang dyno puts more strain on the driveline choking up horsepower. I think this seems more realistic.
then the reading that the dyno gives out should be calibrated for that. just because it puts more strain on the drive line doesn’t mean the reading has to be lower. that should be accommodated for when they design the formula that outputs the horsepower value.
you can calculate moments about a point numerous different ways and you will still arrive with the same answer. thats all this is, different ways to get a horsepower and torque value. i dont know how million dollar companies can mess something like that up.
not arguing with you. just making a point
All arguing aside though, I agree the dyno, regardless of it’s numerical accuracy, is a great tuning tool, because when tuning, you’re only looking for a relative measurement, not absolute.
I also agree that having accurate horsepower number is not a HUGE deal, in the real world.
I am just frustrated by the fact that something so expensive can be so inaccurate…
the coast down procedure tares out all discrepancies and adjusts the dyno sets back to the manufacturer specified targets.
its not inaccurate at all. compared to other dynos, the outputted numbers are different, but neither are correct because proper procedure isnt followed for comparison purposes. theyre only good for essentially base lining themselves.
technically 2 would be wrong since three produce different numbers… and also we should just call myth busters already!!!
they have the funding to make one from the ground up and then compare to existing dynos.
=)
so are you saying that if all different makes measure hp/tq on their vehicles differently they could say that their car comes with more crank hp than the other make because they used a different dyno system…? isnt their some sort of standard.
would crank hp/tq be the standard and the whp/tq be the value that is skewed consistently by dynos due to different measuring techniques?..
i hardly know what im talking about but this is rediculous…
edit: so if ford used a different measuring technique than nissan then ford could say that their engines make more power. but when compared on the same dyno nissan measured more? (hypathetical scenario)
holy shit. i said the answer twice!
the dyno needs to be calibrated to manufacturer provided specs of the vehicle, not the other way around. if its not, the only thing the resulting measured numbers are good for are baseline comparisons to themselves. done deal. case closed. jesus.
that is why one dynos numbers are completely different to anothers even with the same car. unless the coast down is performed properly on both dynomometers, comparing numbers to another dyno is retarded. once a new dyno is used, you might as well try and eat with your butthole instead of your mouth, because nothing matters anymore.
btw nice freakin shop STM.
so basically the issue is not that the tool is flawed, it’s just operator error?
technically yes and no. yes because the proper procedure wasnt performed. no because the operator doesnt car about comparing their numbers with another dyno; theyre more concerned with it staying on the rolls and not getting wheel spin.
edit:
the power numbers are only good for comparison numbers to that exact dyno at those exact dyno set. even another dyno set, in this case weight, is technically incomparable because the dyno’s parasitics arent linear. the coast down procedure will eliminate all variabilties.
Ok. Thank you I understand
Oh SNAP!
OK so I read most of the posts and what you are saying is the Nissan Dyno reads at about half what every other dyno reads at and this logically explains the impossible times of the GT-R at The Ring? 
I still don’t believe that there is not a way of getting an accurate measurement. Toyota could say the Prius is 2000hp.
THIS IS ALL ABOUT CALIBRATION
SHUT UP
CAPSOMGWTF
I understand that spec but, take an Evo for example. If you change the load on the motor, the ecu will run off of a different part of the map. That change in input will result in a change in output (horsepower).
Technically if you wanted to calculate horsepower to get a number, you could do it without a dyno. Just by looking at acceleration, mass, and distance. Like what a drift box does. A dyno is used to load the motor for tuning.