i know, I know.
Don't take dyno numbers too seriously.

But we all want the highest numbers possible right?
For bragging rights and to just feel good about our bikes.

So now I've been told by some pretty experienced guys that different dyno's can produce different results?
Different brands, differing ways of taking measurements, dyno age, user, etc.

Is this all true?

And if so, why is there not some kind of dyno constant (like scales) so results give accurate information relative to other dyno's?

Is it possible a bike with a 185HP dyno result could in fact be similar to a 200HP dyno result due to dyno discrepancies and irregularities?

Seems crazy to me.

* Last updated by: yannih on 6/19/2015 @ 10:19 AM *

So now I've been told by some pretty experienced guys that different dyno's can produce different results?
Different brands, differing ways of taking measurements, dyno age, user, etc.
Is this all true?

Hi there, Yannih!

That's what I've always been told too. Seems like you can pretty much bet on it. Also, the temperature and humidity have a lot to do with it. Dynos are great tools to judge the hp difference before and after mods/tuning but only if done on the same day under all the same conditions. You can't take the actual number as gospel but the difference is a good indication of how the bike compares. You also do not have the ram air effect on a dyno although some shops try to simulate it by blasting a leaf blower at the intake.

They should have some way of calibrating dynos. I imagine that would require running an engine that's guaranteed to make x number of hp at x rpm in any weather (not to mention adjusting for altitude). That is a lot more complicated than acquiring a specific volume of brass. We know exactly how much a cubic meter of brass should weigh and it will never change no matter how old that block of brass gets.

Ideal Dyno Run:
0. Sea level is 0 feet.
1. Room temp = 70°F
2. BARO air pressure = 29.29 (? but you get the idea of the ideal)
3. Engine temp = 240+°F (heat makes HP... too little, not enough heat. too much heat she drops hp, etc.)
4. Tire grip = ??? (slips on the roller is accuracy out the window)
5. Tire pressure = ??? (grip factor is too cold slips, too hot slips, find the ap, just right = grip)
6. Cleaned 02 sniffer. (a well maintained dyno machine for best results).
7. Calibrated dyno APS (air pressure sensor) so it matches 29.29 if that's the matching pressure in the room, or there goes the calc out of hp counts.

Look at your ideal pull factor: temp, baro, elevation and waiting for that day to happen is now take a dyno run at it. Heat the bike to 240+ and now pull at that short window.

Guys, Im not talking varying conditions.
Im talking varying dyno's.
As in 2 different dyno's with the same bike and conditions giving differing results.

As I understand it they can calibrate them to get higher numbers

they call those "happy" dynos

I would wait for ambient atmospheric conditions of 1013hPa and 294 Kelvin for testing.

Dyno numbers are completely useless..... It doesn't matter how many times you beat people over the head with the truth they just keep getting up and re-spouting the same garbage. DYNO NUMBERS DON'T MATTER The AFR line and before/after dyno results are all that matters. Your clutch hand and riding abilities are things to be proud of. Not a piece of paper with meaningless peak numbers.

As in 2 different dyno's with the same bike and conditions giving differing results.

Dynos sold:
I need 5 thousand rollers at this spec. I think if it made in a production run, a pound of butter out of the machine is a pound, yes or no? So say this places most of the dynos as same-spec.

Dyno new: I would now start in on the roller bearings and how well they are broken in, drag vs. new is going to give up some ponies, not horses.

Dyno used: Roller cage again is now in question against less/more drag of the new bearings. So this well broken in roller is nice and loose say, so less drag in theory. Too worn, the rollers now skip or drag, no longer roll and here comes the surface galling and dirt crushed in leaving friction to add to.

Dyno software: Can't see a change in the program if the X to Y is constant. Can't be a pinglitch, because the hardware is fixed as in every dyno, so back to the mechanicals to lower HP.

Dyno roller pad wear: This is a well used dyno, roller has that one tire patch over and over are the wheels about to slip during the test. Bearing, roller, and what else?

Dyno operator: Not too much can go wrong, you wait for 2,000 rpm, WOT the throttle, press the sample button, hit redline, lift off the throttle, hit the end button... read the results.

I would wait for ambient atmospheric conditions of 1013hPa and 294 Kelvin for testing.

If you think about it...
0 alt = Florida
70° = About average for Fla.?
29 and change = About average for Fla.?
240° = Get dem nascar engines near 260°F the HP drops off

Signed,

Smokey's Variables To Tuning
"Best Damn Temps In Town"

Like hub said every dyno is different. Ether by specs or Technology used to read load. I have been on a lot of different kind of dynos with my cars over the years. Dynos usually have a max load rating and as cars start making more power the way of reading it has changed. It's all mathematical equation that's it. Now if you want to manipulate the numbers you can. Tell the operator to put the ambient air temp sensor in the hottest spot he can find and this will change the correction factor. I have seen people/shops do this to make the numbers look better for what ever reason. Maveric hit it on the head don't worry about the numbers the dyno is just a tuning tool that's what it was made for we as egotistical man have turned it to an number reader.

Yep just a tuning tool. My 88 mustang laid down 340rwhp, but ran a series of 11.08's@122 mph at 3200lbs race weight. That was through a 5 speed also so there was no torque converter skewing the dyno #s.

It just seems ridiculous to me that there is no constant that all dyno's are calibrated to.
But it is what it is. Just live with it i guess.
So much for guys posting their dyno run HP results.
Pretty much pointless...

* Last updated by: yannih on 6/19/2015 @ 10:17 AM *

That's right Yannih. Dyno horsepower results are pointless. Now we just need to educate the rest of the forum.

Dynos are at best useful for initial tuning & testing, or as a substitution for real time data collection and analysis which most of us can't do. The only real point dyno's have is measuring changes before and after some attempt to improve performance. Pre-mod establishes the baseline, post-mod then verifies the difference. Doing a bunch of mods then putting it on a dyno has little meaning. Doing a bunch of mods, measuring the differences in different conditions or different dyno has little meaning.

Hypothetically we have two people on the forum. Both bought 2015 14Rs, both did the exact same mods, run the exact same oil, both put them on dynos afterwards and posted the results. Ted's results are 199 hp, and Gary's is 209hp. On face value it's reasonable to say Gary's bike must just run better, or maybe it has "special secret factory cams", or maybe Ted just got a lemon. Or maybe they just live 2000 miles apart, the one dyno is run a bit more conservatively and the other a bit more happily. The only meaning would come in if both bikes were dyno'd prior to the mods, and Ted's results were 180 and Gary's were 190. Most likely, the differences were in some variable (environment, fuel, air quality, altitude, dyno, operator, algorithms) etc. and at the same dyno at the same time both bikes would produce very similar output. Or to say, this is the only way to possibly measure both bikes and claim that Ted's is a lemon and Gary's was sprinkled with magic hp fairy dust.

Dyno output graphs are a result of mathematical algorithms. Different algorithms affect how the data coming from sensors is interpreted into what we see as the output graph. Dyno operators can run more conservative algorithms or more loose algorithms. One difference is error correction. The sensors are returning the same amount of data, but different algorithms will take different averages over different times and that sort of thing which can result in more or less peaky numbers.

See http://www.powercommander.com/downloads/DynoManuals/98118103.02.pdf and look for "smoothing"

This is why I like to go to the dyno nights around here and wait around until another zx 14 gets up on the dyno and then I say "hey do mine after his" and then we compare and make sure the correction factor is the same, look at the hp numbers and AF line.