HarleyTechTalk

In a resent thread in the dyno section a sheet was posted with the run conditions and SAE correction factor. Rather than further high jack that thread I thought I would post my comments here.

The run made the following: 
104.27 hp and 112.34 tq at 53.45 degs F, 29.17 in-hg, Humidity 27%, SAE: 0.98

Two comments caught me by surprise.

1) There is more left in that, yet, as the humidity, and baro was not in your corner.

2) Spool it up in July, and it will go. 104- 106 hp sae.

My understand is that the SAE correction is used to address those very issues, so regardless of the change in conditions in statement 1 or 2 the SAE number would remain 104.27 hp, while the uncorrected number will fluctuate with the weather. Am I missing something?

Not really.
In my conditions and C/F factor range during seasons . (Sae .96- 1.08)
When I have a correction factor under 1.00 for sae. At some point when my conditions shift to 1.00- 1.08 (sae)they will hit that previous uncorrected 1.00 and even the previous std at times.
Some of this feed back is from  comparing other dynos also. (Another subject )

Quote from: strokerjlk on January 17, 2013, 05:08:25 PM
Not really.
In my conditions and C/F factor range during seasons . (Sae .96- 1.08)
When I have a correction factor under 1.00 for sae. At some point when my conditions shift to 1.00- 1.08 (sae)they will hit that previous uncorrected 1.00 and even the previous std at times.
Some of this feed back is from  comparing other dynos also. (Another subject )

Ok now I am totally lost. Not in anyway doubting you, just do not understand what you just said. I keep rereading it and it is not clicking for me. Could reword or give some examples of the point you are making? 
Thanks

SAE Corrections are NOT without limits. If you look there is a stickie post in the dyno section "So what does SAE mean on a dyno sheet?" that I spelled out a good part of the SAE requirements and for the most part they are NOT followed. Since the SAE rules are NOT being followed there are larger errors that show up. As such you can see the power numbers vary when they really are not. The only thing these so called SAE numbers are good for is the same dyno in the same conditions to compare before and after.

Playing games to get bigger than real numbers goes on all the time by figuring out how to cheat the system.

Quote from: Steve Cole on January 17, 2013, 05:46:34 PM
SAE Corrections are NOT without limits. If you look there is a stickie post in the dyno section "So what does SAE mean on a dyno sheet?" that I spelled out a good part of the SAE requirements and for the most part they are NOT followed. Since the SAE rules are NOT being followed there are larger errors that show up. As such you can see the power numbers vary when they really are not. The only thing these so called SAE numbers are good for is the same dyno in the same conditions to compare before and after.

Playing games to get bigger than real numbers goes on all the time by figuring out how to cheat the system.

So if the intention is to get good comparison data and not games is there a usable range that will give somewhat meaningful numbers if the exact same conditions cannot be achieved?  I have read that the SAE intended range of air temperatures is 59 to 95 degs F, and the intended range of dry air pressures is 26.58 to 31.01 inHg.

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.

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

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 by SAE, you can toss them in the garbage can as that is where they belong.

Quote from: 1FSTRK on January 17, 2013, 06:00:24 PM

Quote from: Steve Cole on January 17, 2013, 05:46:34 PM
SAE Corrections are NOT without limits. If you look there is a stickie post in the dyno section "So what does SAE mean on a dyno sheet?" that I spelled out a good part of the SAE requirements and for the most part they are NOT followed. Since the SAE rules are NOT being followed there are larger errors that show up. As such you can see the power numbers vary when they really are not. The only thing these so called SAE numbers are good for is the same dyno in the same conditions to compare before and after.

Playing games to get bigger than real numbers goes on all the time by figuring out how to cheat the system.

So if the intention is to get good comparison data and not games is there a usable range that will give somewhat meaningful numbers if the exact same conditions cannot be achieved?  I have read that the SAE intended range of air temperatures is 59 to 95 degs F, and the intended range of dry air pressures is 26.58 to 31.01 inHg.

So you see why I always say,looking at the uncorrected is as important as the other C/F factors.
When comparing on the same dyno.

Quote from: Steve Cole on January 17, 2013, 06:23:36 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.

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

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 by SAE, you can toss them in the garbage can as that is where they belong.

What does uncorrected or corrected have to do with test conditions. The conditions are the conditions. The only thing getting corrected is the hp and tq numbers.

In order to use a SAE correction there are limits to the test conditions allowed. As an example if the air temperature changes over "X" amount between test you CANNOT use a SAE correction to compare the results! Same goes for humidity and pressure. You would need to read the entire specification to see all the limits but for the most part many of the posted dyno charts of before and after are not even close to following the rules as spelled out by SAE. Therefore the results being shown are NOT SAE corrected regardless of what you are told.

If you are only using the results to compare from one run to another on the same exact dyno and the test conditions are the same (humidity, pressure and temperature) then you can but if let say one run has a humidity of 35% and the next run is 5% then comparing the power numbers is meaningless as you are outside the stated SAE rules for a proper correction. This is a game some dyno operators have been playing to make results look better for years.

Quote from: Steve Cole on January 18, 2013, 08:42:16 AM
In order to use a SAE correction there are limits to the test conditions allowed. As an example if the air temperature changes over "X" amount between test you CANNOT use a SAE correction to compare the results! Same goes for humidity and pressure. You would need to read the entire specification to see all the limits but for the most part many of the posted dyno charts of before and after are not even close to following the rules as spelled out by SAE. Therefore the results being shown are NOT SAE corrected regardless of what you are told.

If you are only using the results to compare from one run to another on the same exact dyno and the test conditions are the same (humidity, pressure and temperature) then you can but if let say one run has a humidity of 35% and the next run is 5% then comparing the power numbers is meaningless as you are outside the stated SAE rules for a proper correction. This is a game some dyno operators have been playing to make results look better for years.

I dont think it is really a game with most dyno tuners. Some with a little knowledge, yes.
Truth is more likely to be that there are maybe 4 or 5 dyno people out there that actually do know what they are doing and dont care what the build is, but do know when there is more in the engine than what was shown an the last run.

I know not all tuners play the game but some do, and that's the problem.  Most of the public is not informed enough to understand that there are limits and rules and that they need to be followed in order for the SAE corrected results to mean anything. Let's say you have a dyno guy and he is at 6000' altitude, he is starting with a big disadvantage than the guy at sea level when it comes to peak power numbers. As long as the guy at 6000' makes runs and the test conditions stay within the SAE limits then his results from his dyno can be compared to each other but not necessarily with the dyno that's at sea level. Same goes for the guy at sea level, you have to stay within the SAE test limits and rules for the numbers to mean anything. The dyno is a good tool just like any other tool it can be used improperly. Trying to compare results from one dyno to another for the most part, is just wishful thinking when it comes right down to the numbers though. It does give you a rough idea but the variation from making run to run on the same dyno one after the other is about 3-4% at best on a DynoJet dyno. So at 100 HP that gives a range all by itself and if your within that range it's almost impossible to say you gained or lost power just by the numbers themselves. You can have a change of that same 3-4% just by the conditions changing that the test is being performed in. So one needs to be careful and know what to look at outside of just a set of numbers printed as SAE correct.

As for looking at any one combination and saying there is more in it all depends on how familiar you are with the build in question. The most important thing to me is that you are happy when you ride the bike as that is what counts.

Quote from: strokerjlk on January 17, 2013, 05:08:25 PM
Not really.
In my conditions and C/F factor range during seasons . (Sae .96- 1.08)
When I have a correction factor under 1.00 for sae. At some point when my conditions shift to 1.00- 1.08 (sae)they will hit that previous uncorrected 1.00 and even the previous std at times.
Some of this feed back is from  comparing other dynos also. (Another subject )

Could you post an example graph showing this?

Quote from: Steve Cole on January 18, 2013, 08:42:16 AM
In order to use a SAE correction there are limits to the test conditions allowed. As an example if the air temperature changes over "X" amount between test you CANNOT use a SAE correction to compare the results! Same goes for humidity and pressure. You would need to read the entire specification to see all the limits but for the most part many of the posted dyno charts of before and after are not even close to following the rules as spelled out by SAE. Therefore the results being shown are NOT SAE corrected regardless of what you are told.

So you miss spoke when you used the term uncorrected test conditions Because all test conditions are uncorrected and that was what was confusing.

Quote from: Steve Cole on January 18, 2013, 08:42:16 AM
If you are only using the results to compare from one run to another on the same exact dyno and the test conditions are the same (humidity, pressure and temperature) then you can but if let say one run has a humidity of 35% and the next run is 5% then comparing the power numbers is meaningless as you are outside the stated SAE rules for a proper correction. This is a game some dyno operators have been playing to make results look better for years.

I will agree that games are played to sell but games to discredit the dyno to cover parts that did not deliver and tunes that will degrade are also played. The dyno used as a tool with every reasonable effort made to be accurate is still the best we can do. I have just seen to many runs made on different dynos by honest operators give repeatable results to be told otherwise. The shop that does my work has been building motors and using dynojet dynos for 20 years. Not only have I seen bikes make the same power when he tests them here year after year, but he has built and tested motors here that go to Daytona to run in the Horsepower shootout on Dynojet dynos operated by people from dynojet that make the same corrected power there that they made here before they left and I have seen the graphs and over 2 dozen trophies that prove it. I personally have come to believe that much of what is blamed on these machines is just poor set up and maintenance. I do know the 250I with the dyno stack in the machine will need to be watched or altered to achieve accurate temperature readings but there again that is the operator's responsibility to make sure the temp on the screen is the same as the air temp at the air cleaner inlet. Let us not confuse the integrity of the machine with the integrity or ability of the operator.

The reason I used the words uncorrected test conditions as I have seen people who have entered corrected conditions into a dyno for it to calculate from. Many dyno's out there allow people to enter the temperature along with the wet and dry bulb measurements. The early Dynojets had a box you had to mount with the temp probe hanging out of it. I saw more than a few people who had them mounted back towards the exhaust exit! I just wanted to be sure to cover that. As far a dyno being the best we have that is very true but right along with that is an operator that checks everything to keep it that way.

Its no different than anything else as long as people know about it and it seems most think, from what I see, that because the sheet says SAE that it truely is. There are many dyno sheets that I have seen where the test conditions from the baseline to the after run show 30% humidity changes along with temperature changes in the 30 degree range. The owners thinks because the sheet says SAE correction that its all OK when in truth it's not even close to true. I believe the dyno machine software could and should flag those differences when they are clearly outside of the SAE specification. Better yet the operator just should not do it but that falls into your last statement "Let us not confuse the integrity of the machine with the integrity or ability of the operator." There is just a whole lot more to it than tossing the bike up on a dyno and running it to print off a dyno sheet.

To get back to the OP, with a properly set up and operated dyno there should be no way that certain readings of temp, baro, and humidity should give significantly more favorable results in SAE. If this is occurring it is often a sign that that something is wrong with the dyno set up. As I said I have seen where the stack is reading a much different temp than the thermometer on the wall and therefore the correction is based on stack temp and not room temp which is where the bike gets its air. If the stack temp ranges from 75 to 100 degs while the room temp only varies from 68 to 81 degs then you will have inaccurate correction factors generated.

I liked the older probe where you could hang it by the intake. I have 2 indoor outdoor temp gauges. I put one of outdoor units by my intake and one by my weather stack. Which is outside of my dyno. About the same height as the intake.  I use these to double check along with weather from an airport 2 miles away.  I am more concerned about repeatable results than over inflated happy numbers. I can do more with mine with repeatable results. If I swing 12% on my correction factor. That is not acceptable to me. Unless a front moves in or out with weather. If I saw 12%. I would change my set up. This is how I use and read what I'm doing. It is not perfect but it is the best I got going. You can see between these 2 sets of runs. I made power and tuned out dip. Where this happens on the scale is less of a concern than shape and movement. 

So in the above example you gained 12.56hp uncorrected from run 002 to run 105 but only gained 9.87hp SAE corrected with the tune because 2.69hp of the uncorrected gain was due to improved weather conditions.  Which is to say if all the runs were made in the exact same weather conditions you would have seen a 9.87hp gain if viewed in either SAE or uncorrected format for these runs.

And runs 4,5,6,7 are the same as corrected.  Correction of 1.00 is none. The rest is just percentages. The dyno can give lots of good info. Mine gives pretty decent repeatable results.

It seems that some think that waiting for good air will somehow give them a large advantage. The purpose of the correction factor is to remove that advantage as much as possible so stating that the motor has more power left in it is not really true. The motor once fully tuned is making all it can after that the only thing that will have more power in it is the intake air as the conditions change for the better. The statement is like saying the motor has more in it after we add Nitrous but we don't compare Nitrous motors to naturally aspirated motors because it is an unfair comparison. They seem to want to say uncorrected numbers are the real numbers when they test in really good air and they come up higher than the corrected numbers.

Look at the 110 cvo w/ 577 dyno sheet.  Not picking on Steve but he is showing a 22% correction factor.  24hg doesn't help, but that is his elevation.  If corrected is higher or lower than STD or SAE depend on my weather.  I bet Steve never see's his corrected go higher than STD or SAE, but he is at what? 5000ft.  His pressure will always be low.

Quote from: hrdtail78 on January 24, 2013, 03:18:20 PM
Look at the 110 cvo w/ 577 dyno sheet.  Not picking on Steve but he is showing a 22% correction factor.  24hg doesn't help, but that is his elevation.  If corrected is higher or lower than STD or SAE depend on my weather.  I bet Steve never see's his corrected go higher than STD or SAE, but he is at what? 5000ft.  His pressure will always be low.

So what is your point?

You tune a motor and it makes 100hp uncorrected. The customer leaves happy. He comes back from Sturgis where he ran it on the dyno to show everyone and it made 78.74hp uncorrected. The graph looks perfect just low. Was the Sturgis dyno wrong, was something wrong with your dyno, or is something wrong with the motor?

A couple more questions to add is:  What was headtemp bike was pulled at, was the whole bike heat soaked or just engine.  Bike ran through downtown, made to Full throttle, shut off, waited in line for 10 min, and then pulled could be 250 something headtemp.  But.... the correction factor is suppose to take care of that for us.  That all depends on maint. of the dyno, and stack.  DJ wants you to send your stack in annually, but you have to do it at least every other to remain on there list as an authorized tuner.  Some tuners send it in annually and some have never been sent in.  I know a guy that use to contact cleaner his connectors on a weekly basis.  Your weather stack has a fan in it.  Just like a computer.  It needs the dust blown out.  Leads me to believe you could travel around to different dyno's with a weather stack and be good.  Too many differences in the dyno's, and operators.

Quote from: 1FSTRK on January 24, 2013, 03:21:30 PM

Quote from: hrdtail78 on January 24, 2013, 03:18:20 PM
Look at the 110 cvo w/ 577 dyno sheet.  Not picking on Steve but he is showing a 22% correction factor.  24hg doesn't help, but that is his elevation.  If corrected is higher or lower than STD or SAE depend on my weather.  I bet Steve never see's his corrected go higher than STD or SAE, but he is at what? 5000ft.  His pressure will always be low.

So what is your point?

There has to be a tolerance for the correction factor.  I have read 10% but I'm not sure.  This site chose SAE.  Probably because it's the most modest.  Numbers are numbers.  Without max values on the sheets posted above.  You still see what you are after while tuning.  Improvement.  I also like to look at time.  Faster you can red line.  Faster you can spin the back tire on the street.

Quote from: 1FSTRK on January 24, 2013, 03:53:08 PM
You tune a motor and it makes 100hp uncorrected. The customer leaves happy. He comes back from Sturgis where he ran it on the dyno to show everyone and it made 78.74hp uncorrected. The graph looks perfect just low. Was the Sturgis dyno wrong, was something wrong with your dyno, or is something wrong with the motor?

Now the rest of the story, there was nothing wrong with either dyno or the bike. Both dyno runs were properly performed and gave accurate results, the bike made less power because of the conditions. This is where corrected data comes in.

The first run was in the spring at sea level with a high pressure system in the area with these conditions.
Temp 59.5, Pressure 31.0, Hum.5%      SAE correction = .915       
Uncorrected 100hp        SAE 91.5hp

The second run in August at Sturgis which is known for bad conditions resulted in this.
Temp 95.0, Pressure 27.5, Hum. 82%   SAE correction=1.162       
Uncorrected 78.74hp     SAE corrected 91.5hp

The same effect happened in the runs you made above which is why I pointed out that 2.69hp of the uncorrected gain was due to the weather change alone. I am not taking away from the tuning job or saying anything could have been done better, but what if the bike came in tuned and you made some fine adjustments that made a 2.69 hp improvement and during that time the condition got worse by the same amount? The uncorrected info would show that you made the same power at beginning and end, but the corrected would put the 2.69 lost by weather changes back in and then would show a 2.69 gain that you made with the tuning.

Guess I misunderstood your question.