Author Topic: So what does SAE mean on a dyno sheet?  (Read 6034 times)

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Offline Steve Cole

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So what does SAE mean on a dyno sheet?
« on: April 24, 2012, 04:29:51 PM »
 I figure this could be a spot for people to talk about what it is and what it means. Let's here what people believe it to mean then we can bring in what it really means!

For the record there is NOT one dyno sheet from a bike dyno that is really corrected per SAE Standards, so if you want to argue that point it's a waste of time.
« Last Edit: April 24, 2012, 05:27:15 PM by Coyote »
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Offline harleytuner

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Re: So what does SAE mean on a dyno sheet?
« Reply #1 on: April 24, 2012, 04:51:17 PM »
SAE= Society of Automotive Engineers.  Correction factor takes Uncorrected dyno results and corrects them to certain atmospheric conditions.  I.E. SAE corrects to 29.23InHg(99KPA) of dry air and 77 deg. Farenheit (25 C).


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Offline Steve Cole

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Re: So what does SAE mean on a dyno sheet?
« Reply #2 on: April 24, 2012, 05:01:50 PM »
Per SAE J1349

Reference atmospheric conditions and test ranges for which correction factors are valid.


REFERENCE ATMOSPHERIC CONDITIONS

                                                    Standard                       Test
                                                    Condition                 Range Limits

Inlet Air Supply Pressure (absolute) 100 kPa                       ----
Dry Air Pressure (absolute)               99 kPa                 90 kPa – 105 kPa
Inlet Air Supply Temperature              25 °C                  15 °C – 35 °C

With the exception of humidity, no modification to the composition of intake air is permitted.
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Offline Tattoo

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Re: So what does SAE mean on a dyno sheet?
« Reply #3 on: April 24, 2012, 05:08:02 PM »
Ok ,what does STD stand for..
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Offline harleytuner

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Re: So what does SAE mean on a dyno sheet?
« Reply #4 on: April 24, 2012, 05:19:33 PM »
STD= standard.  It's an older correction factor.  it corrects to
60-degrees F, 29.92inHg and 0-percent humidity.

SAE came along because the majority of vehicles were built in Detroit, so they changed the conditions to Detroits average conditions.
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Offline Slyde

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Re: So what does SAE mean on a dyno sheet?
« Reply #5 on: April 24, 2012, 05:19:42 PM »
I'm probebly wrong but does it matter?

If you can get as much area beneath each curve, havn't you succeeded?

Does it matter if it's SAE, STD or Uncorrected? If you tune to any standard the best you can, the tune doesn't change between them does it?


Offline harleytuner

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Re: So what does SAE mean on a dyno sheet?
« Reply #6 on: April 24, 2012, 05:21:10 PM »
I'm probebly wrong but does it matter?

If you can get as much area beneath each curve, havn't you succeeded?

Does it matter if it's SAE, STD or Uncorrected? If you tune to any standard the best you can, the tune doesn't change between them does it?

It doesn't change the tune, it's only in the way the results are printed.  IE after a bike is tuned, you can print out any correction factor you want.  SAE, STD, UNCORRECTED, DIN, JIN etc.
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Offline FLTRI

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Re: So what does SAE mean on a dyno sheet?
« Reply #7 on: April 24, 2012, 05:52:48 PM »
IMO, SAE is the most critical correction and the best one to use to use for comparison purposes.

While there is no way, without lab equipment, to assure 100% SAE compliance we can remove and reduce as many variables as we have control over.

This will produce the best case scenario for comparison IMO, as long as everyone agrees that anything under 3hp/tq is acceptable error rate.

Also it is questionable to expect accurate comparisons (<3hp-tq) when comparing 6000 elevation graphs to sea level graphs as the correction factoring is just too far out of SAE specifications.

This does not mean that all 6000ft graphs are not comparable, just might have a larger error rate than +/- 3hp-tq to consider.

As always, JMHO,
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Offline hrdtail78

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Re: So what does SAE mean on a dyno sheet?
« Reply #8 on: April 24, 2012, 06:02:27 PM »
IMO, SAE is the most critical correction and the best one to use to use for comparison purposes.

While there is no way, without lab equipment, to assure 100% SAE compliance we can remove and reduce as many variables as we have control over.

This will produce the best case scenario for comparison IMO, as long as everyone agrees that anything under 3hp/tq is acceptable error rate.

Also it is questionable to expect accurate comparisons (<3hp-tq) when comparing 6000 elevation graphs to sea level graphs as the correction factoring is just too far out of SAE specifications.

This does not mean that all 6000ft graphs are not comparable, just might have a larger error rate than +/- 3hp-tq to consider.

As always, JMHO,
Bob

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Offline Slyde

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Re: So what does SAE mean on a dyno sheet?
« Reply #9 on: April 24, 2012, 06:04:29 PM »
I guess my point(or question) was this. It doesn't really matter what correction factor is used does it? It's an equation. A bike makes X HP and Y TQ when it's tuned correctly. If it's tuned correctly 5000 feet, brought down to 1000 and tuned again, the tune shouldn't change very much, right? Just the numbers, the curves should remain the same? That's assuming it's a FI and the sensors have remained valid?

EDIT;
I do understand that the numbers indicated are fun to throw around...but that might be all they are good for. That is JMHO.
« Last Edit: April 24, 2012, 06:12:03 PM by Slyde »

Offline 14Frisco

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Re: So what does SAE mean on a dyno sheet?
« Reply #10 on: April 24, 2012, 06:22:41 PM »
I guess my point(or question) was this. It doesn't really matter what correction factor is used does it? It's an equation. A bike makes X HP and Y TQ when it's tuned correctly. If it's tuned correctly 5000 feet, brought down to 1000 and tuned again, the tune shouldn't change very much, right? Just the numbers, the curves should remain the same? That's assuming it's a FI and the sensors have remained valid?

EDIT;
I do understand that the numbers indicated are fun to throw around...but that might be all they are good for. That is JMHO.

It can/does matter to you too.
Example: The tuner starts tuning at 9 AM at certain conditions (temp, humidity etc.) and records runs.  The tuner finishes tuning at 1 PM at certain other conditions (warmer temps, etc.).  To be able to more accurate compare the runs recorded at 9 AM (and 10 AM and...) with the runs at 1 PM, it is valuable to normalize the results to SAE (or any standard that is able to normalize the results).

Similarly, if you bring back the bike to the same dyno 6 months later - if you want to be able to compare the new runs with the results from 6 months earlier it helps if the results are normalized to SAE.

Offline Steve Cole

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Re: So what does SAE mean on a dyno sheet?
« Reply #11 on: April 24, 2012, 06:55:07 PM »
All of you are making good points but here is another little piece of the SAE standard.

Inlet Air Conditions

The pressure, temperature, and humidity of the engine’s inlet air supply shall be controlled as close to the standard
reference conditions as possible to minimize the correction factor. The inlet air pressure temperature and humidity
shall not deviate from the controlled set points by more than 3% for the entire test.


Instrumentation Accuracy

The following minimum test instrumentation accuracy is required:
1. Torque—±0.5% of measured value
2. Speed—±0.2% of measured value
3. Fuel Flow—±1% of measured value
4. General Temperature measurements—±2 °C
5. Inlet Air Temperature—±1.0 °C

What happens when you do not follow the specifications?
What happens when you do not directly measure Torque as required in the specification?
What happens when measurements are being taken with equipment WORSE than required by the specification?
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Offline Slyde

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Re: So what does SAE mean on a dyno sheet?
« Reply #12 on: April 24, 2012, 07:05:43 PM »
I guess my point(or question) was this. It doesn't really matter what correction factor is used does it? It's an equation. A bike makes X HP and Y TQ when it's tuned correctly. If it's tuned correctly 5000 feet, brought down to 1000 and tuned again, the tune shouldn't change very much, right? Just the numbers, the curves should remain the same? That's assuming it's a FI and the sensors have remained valid?

EDIT;
I do understand that the numbers indicated are fun to throw around...but that might be all they are good for. That is JMHO.

It can/does matter to you too.
Example: The tuner starts tuning at 9 AM at certain conditions (temp, humidity etc.) and records runs.  The tuner finishes tuning at 1 PM at certain other conditions (warmer temps, etc.).  To be able to more accurate compare the runs recorded at 9 AM (and 10 AM and...) with the runs at 1 PM, it is valuable to normalize the results to SAE (or any standard that is able to normalize the results).

Similarly, if you bring back the bike to the same dyno 6 months later - if you want to be able to compare the new runs with the results from 6 months earlier it helps if the results are normalized to SAE.

Good examples, thanks, I agree.

So again, it seems like it doesn't matter what correction factor is used, as long as one is used and as long as it's not uncorrected. It's just the numbers that differ.


Offline harleytuner

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Re: So what does SAE mean on a dyno sheet?
« Reply #13 on: April 24, 2012, 07:35:15 PM »
The main thing is is that the correction factors are for comparison purposes.  Compare apples to apples.  It does us no good to compare same builds printed in differn't CF's.  For me, I could care less about comparing my build to other builds, I know what I have.  But, I typically change my bike and full tune it 3 - 6 times a year, I like to compare my builds to see what gains (or losses) I am getting.  I don't take to much stock in what other peoples dyno's are getting, there are more variables than the CF anyways, what gear the bike is run in being one of them.  I run the bikes I tune in 4th gear, some people run in 5th and even 6th, so it isn't a good comparison between what I run and what they run even if they print in the same CF as me. 
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Offline Admiral Akbar

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Re: So what does SAE mean on a dyno sheet?
« Reply #14 on: April 24, 2012, 10:12:22 PM »
Quote
The following minimum test instrumentation accuracy is required:
1. Torque—±0.5% of measured value
2. Speed—±0.2% of measured value
3. Fuel Flow—±1% of measured value
4. General Temperature measurements—±2 °C
5. Inlet Air Temperature—±1.0 °C

I guess that leaves out dynojet,,  :wink:

Max
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Offline Rider57

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Re: So what does SAE mean on a dyno sheet?
« Reply #15 on: April 25, 2012, 12:39:28 AM »
All of you are making good points but here is another little piece of the SAE standard.

Inlet Air Conditions

The pressure, temperature, and humidity of the engine’s inlet air supply shall be controlled as close to the standard
reference conditions as possible to minimize the correction factor. The inlet air pressure temperature and humidity
shall not deviate from the controlled set points by more than 3% for the entire test.


Instrumentation Accuracy

The following minimum test instrumentation accuracy is required:
1. Torque—±0.5% of measured value
2. Speed—±0.2% of measured value
3. Fuel Flow—±1% of measured value
4. General Temperature measurements—±2 °C
5. Inlet Air Temperature—±1.0 °C

What happens when you do not follow the specifications?
What happens when you do not directly measure Torque as required in the specification?
What happens when measurements are being taken with equipment WORSE than required by the specification?
All correct. In a CCR, (Climate Controlled Room) all these items are controlled by a stand alone computer that has the sole purpose of being a super-duper weather station that controls the weather in the CCR.
Other factors include Parasitic loss and calibration. This is affected by dyne motor heat, bearing conditions.
For EO type acceptance, all dyne calibrations have to be performed within 10 minutes of the test.
Gas analyzer calibrations must be performed within 15 minutes of the test.
Don't follow the specifications? Invalid test results. Test specifications are entered into the computer so these mistakes are rare but do and did happen.
Torque must be a direct measurement. Not secondary as you would derive from a eddy current motor / brake.
Use junk to do the test and you have junk for a result.
Crap, starting to feel like I'm back at the EPA!
Thanks a lot Steve!!LOL
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Offline harleytuner

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Re: So what does SAE mean on a dyno sheet?
« Reply #16 on: April 25, 2012, 03:45:39 AM »
All of you are making good points but here is another little piece of the SAE standard.

Inlet Air Conditions

The pressure, temperature, and humidity of the engine’s inlet air supply shall be controlled as close to the standard
reference conditions as possible to minimize the correction factor. The inlet air pressure temperature and humidity
shall not deviate from the controlled set points by more than 3% for the entire test.


Instrumentation Accuracy

The following minimum test instrumentation accuracy is required:
1. Torque—±0.5% of measured value
2. Speed—±0.2% of measured value
3. Fuel Flow—±1% of measured value
4. General Temperature measurements—±2 °C
5. Inlet Air Temperature—±1.0 °C

What happens when you do not follow the specifications?
What happens when you do not directly measure Torque as required in the specification?
What happens when measurements are being taken with equipment WORSE than required by the specification?

right, most dyno rooms can correct the end results to a correction factor,  BUT, they don't take in account how the bike is running in the conditions.  The other tuner and myself just had this discussion last week at the shop. 
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Offline Steve Cole

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Re: So what does SAE mean on a dyno sheet?
« Reply #17 on: April 25, 2012, 09:21:25 AM »
So the bottom line to all this is that the specification controls what must be done in order for it to have repeatable meaning. You can go to one place and get the same results as you did in another PROVIDED ALL OF THE SPECIFICATION is followed, not just part of it. Leave out one part, any part, and it doesn't count.

All of the aftermarket chassis dyno's are only a method to compare what a bike is doing in it's running condition at that day in time, nothing more or nothing less. This goes for any and all of the so called correction factors, as NONE of them are truely correct with what is being done today. They are nothing more than company's (insert brand here) way of adding something as a correction factor. What those correction factors truely are no one knows as they are NOT SAE, STD, STP or any other real specification.

To try and compare results is all fine and dandy but the truth is it doesn't work unless meaningful specifications are followed. A harley engine power output will vary day to day, conditions change throughout the day and the power follows right along. So when you see dyno charts that compare two runs and the uncorrected test conditions vary more than the 3% total range, that is allowed, you can toss them in the garbage can as that is where they belong.

Now to use the results by applying "X" correction factor as a way to see relative numbers is fine provided they ALL use the same correction factor. If we look at DJ as an example that doesn't work as DJ changed there correction factors somewhere along the way. I believe to-date there have been 3 sets of changes to the DJ dyno's corrections but I could be wrong on the amount of changes.
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Offline glens

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Re: So what does SAE mean on a dyno sheet?
« Reply #18 on: April 25, 2012, 12:08:15 PM »
This goes for any and all of the so called correction factors, as NONE of them are truely correct with what is being done today. They are nothing more than company's (insert brand here) way of adding something as a correction factor. What those correction factors truely are no one knows as they are NOT SAE, STD, STP or any other real specification.

... If we look at DJ as an example that doesn't work as DJ changed there correction factors somewhere along the way. I believe to-date there have been 3 sets of changes to the DJ dyno's corrections but I could be wrong on the amount of changes.


Check out http://www.hotrod.com/thehistoryof/113_0603_dynojet_chassis_dyno/viewall.html

It's an article from 2006.  Search for the paragraph about 1/3 of the way down, starting with "One of the biggest headaches".  That and the following paragraph are eye-openers.  That was talking about the 100.  I don't know what if anything is different with the current stuff.


Offline wurk_truk

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Re: So what does SAE mean on a dyno sheet?
« Reply #19 on: April 25, 2012, 12:48:05 PM »
HAHA...  I remember all of that....  and, I am sure that all carries thru to today.  IIRC, there was a bruhaha and they altered the math a little.  All the dyno companies do this, too.  These are true and simple made up numbers we all see from chassis dynos. The 'numbers' have not too much basis in reality, its all about the internal math.  Back in the day, there was a huge disrepency between Dynojets and Mustang dynos (for hot rods).

 But... it is (should be) a way to keep score on upgrades, etc.  In the Harley world, and most bikes... the Dynojet is the de facto leader and all numbers eventually get compared to this.  Just like James1931 just bought a Factory Pro...  different math inside and different numbers outside.

As far as 'tuning' goes, none of this really matters.  What matters is the guys that make a living making more HP and TQ, like cam, head, and exhaust companies.

And... as far as Steve at GMR having those big correction factors?  Thats fine, I guess...  I imagine the 'numbers' are close if one takes it to sea level.  WHat cracks ME up is this... as that bikes (or bikes) stand... that 14hp motor is really only making 112hp. at that altitude.  Steve can have it 'both ways' kind of and that allows him to test parts with WAY less stress than someone at sea level.
« Last Edit: April 25, 2012, 12:55:03 PM by wurk_truk »
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Offline autoworker

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Re: So what does SAE mean on a dyno sheet?
« Reply #20 on: April 25, 2012, 01:16:22 PM »
I guess that leaves out dynojet,,  :wink:

Max

Which model? :unsure:
It must be true,I read it on the internet.

Offline Admiral Akbar

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Re: So what does SAE mean on a dyno sheet?
« Reply #21 on: April 25, 2012, 01:59:07 PM »
I guess that leaves out dynojet,,  :wink:

Max

Which model? :unsure:

All of them??  :nix:

Max

Add: unless you have  a standard to compare against that puts out the same range of HP/tq to the drum as the bike you are testing..

Max
« Last Edit: April 25, 2012, 02:01:24 PM by Max Headflow »
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Offline BlackSpecial

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Re: So what does SAE mean on a dyno sheet?
« Reply #22 on: April 25, 2012, 02:27:44 PM »
Quote
Check out http://www.hotrod.com/thehistoryof/113_0603_dynojet_chassis_dyno/viewall.html

It's an article from 2006.  Search for the paragraph about 1/3 of the way down, starting with "One of the biggest headaches".  That and the following paragraph are eye-openers.  That was talking about the 100.  I don't know what if anything is different with the current stuff.


I was wondering if that article would turn up in this thread.  Very revealing admissions by Dobeck.
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Offline Admiral Akbar

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Re: So what does SAE mean on a dyno sheet?
« Reply #23 on: April 28, 2012, 02:03:45 PM »
So it sounds like you need a Yamaha V Max to calibrate your dyno..  :scoot:
Max
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Offline FLTRI

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Re: So what does SAE mean on a dyno sheet?
« Reply #24 on: April 28, 2012, 06:19:38 PM »
Somebody had to create and set the standard and Dobeck was the dude.
Everyone has followed his lead.
I use Dynojet 250I because we wanted an accepted system for comparison and Dynojet was the unit.
JMHO,
Bob
« Last Edit: October 20, 2012, 02:50:46 PM by FLTRI »
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