STD Correction Factor
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On The Tree
Joined: Mar 2014
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From: Lakeville, MN
STD Correction Factor Do any Dyno operators have some inside knowledge regarding the STD correction factor?
I am creating a calculator for converting between SAE, STD, and Uncorrected. The numbers I am getting for SAE and Uncorrected appear to be within the expected margins of error, however when it comes to STD I am producing a larger correction factor than the Dynojet software.
Even more interesting is that my numbers seem to match those of some other calculators I have found online. Here is one example from Wallace Racing.
Here is mine.
I am creating a calculator for converting between SAE, STD, and Uncorrected. The numbers I am getting for SAE and Uncorrected appear to be within the expected margins of error, however when it comes to STD I am producing a larger correction factor than the Dynojet software.
Even more interesting is that my numbers seem to match those of some other calculators I have found online. Here is one example from Wallace Racing.
Here is mine.
Thread Starter
On The Tree
Joined: Mar 2014
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From: Lakeville, MN
I may try that, I suspect I may need to get a hold of someone at Dynojet to get these answers though.
I did find part of the formula in some Ford literature, it looks like STD does not account for water vapor. Accounting for this in my formulas cut the difference by roughly 25% but I'm still missing something.
EDIT: I found the rest of the equation in some more Ford documentation, it looks like STD applies a power of 1.2 to the pressure correction and 0.6 to the temperature. However I'm still coming up with a factor that is much larger than Dynojet's.
EDIT 2: I'm getting closer, I found another guy who has already done the same thing I'm doing. His page is here. He's saying that Dynojet isn't using the 60deg J607 spec for STD but actually 77deg. This change has my math looking pretty good. I also have a hunch Dynojet is not using the J607 formula, but is actually using the J1349 formula with 100% efficiency.
I did find part of the formula in some Ford literature, it looks like STD does not account for water vapor. Accounting for this in my formulas cut the difference by roughly 25% but I'm still missing something.
EDIT: I found the rest of the equation in some more Ford documentation, it looks like STD applies a power of 1.2 to the pressure correction and 0.6 to the temperature. However I'm still coming up with a factor that is much larger than Dynojet's.
EDIT 2: I'm getting closer, I found another guy who has already done the same thing I'm doing. His page is here. He's saying that Dynojet isn't using the 60deg J607 spec for STD but actually 77deg. This change has my math looking pretty good. I also have a hunch Dynojet is not using the J607 formula, but is actually using the J1349 formula with 100% efficiency.
Last edited by InfrareV; Jun 15, 2014 at 09:00 PM.
Actually all of our #s are on SAE Correction and #3 smoothing unless we are working with a customer from another shop who has previous dyno results using a different correction factor. MTI Racing used STD for years so when one of their customers visits our shop we use STD so they can accurately compare their results.
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From: Maricopa, AZ
Do any Dyno operators have some inside knowledge regarding the STD correction factor?
I am creating a calculator for converting between SAE, STD, and Uncorrected. The numbers I am getting for SAE and Uncorrected appear to be within the expected margins of error, however when it comes to STD I am producing a larger correction factor than the Dynojet software.
Even more interesting is that my numbers seem to match those of some other calculators I have found online. Here is one example from Wallace Racing.
Here is mine.
I am creating a calculator for converting between SAE, STD, and Uncorrected. The numbers I am getting for SAE and Uncorrected appear to be within the expected margins of error, however when it comes to STD I am producing a larger correction factor than the Dynojet software.
Even more interesting is that my numbers seem to match those of some other calculators I have found online. Here is one example from Wallace Racing.
Here is mine.
On your calculator, if it's for general public use, make sure to specify what pressure you are asking for. Station Pressure I believe is what your calculator should be using (not sure if I'm remembering correctly). If someone enters Baro Pressure, in that case, the results will be wrong.
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Actually all of our #s are on SAE Correction and #3 smoothing unless we are working with a customer from another shop who has previous dyno results using a different correction factor. MTI Racing used STD for years so when one of their customers visits our shop we use STD so they can accurately compare their results.
I guess he was mistaken? Thread Starter
On The Tree
Joined: Mar 2014
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From: Lakeville, MN
On your calculator, if it's for general public use, make sure to specify what pressure you are asking for. Station Pressure I believe is what your calculator should be using (not sure if I'm remembering correctly). If someone enters Baro Pressure, in that case, the results will be wrong.
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It is closer to 2.5% variance by Winpep. The Dynojet reader.
My one old run STD. Smoothing of 5.
Same run SAE with smoothing of 5.
Calculated by dividing one by the other.
So you can multiple by .9759 to go from STD to SAE or 1.02467 to go from SAE to STD.
All I did was toggle the correction factor on my Winpep software.
So at 600rwhp STD, you are making 585.54 SAE. I have seen a few that wanted to say they had 600rwhp but went to STD. What ever makes you sleep at night. The rest of the world uses SAE and typically 3-5 smoothing.
BTW on my shown pulls, the smoothing from 0-5 made difference of .4hp. So we had a good tach signal to get clean information. I have scene up to 5 hp though with real gittery curves.
My one old run STD. Smoothing of 5.
Same run SAE with smoothing of 5.
Calculated by dividing one by the other.
So you can multiple by .9759 to go from STD to SAE or 1.02467 to go from SAE to STD.
All I did was toggle the correction factor on my Winpep software.
So at 600rwhp STD, you are making 585.54 SAE. I have seen a few that wanted to say they had 600rwhp but went to STD. What ever makes you sleep at night. The rest of the world uses SAE and typically 3-5 smoothing.
BTW on my shown pulls, the smoothing from 0-5 made difference of .4hp. So we had a good tach signal to get clean information. I have scene up to 5 hp though with real gittery curves.
Thread Starter
On The Tree
Joined: Mar 2014
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From: Lakeville, MN
It is closer to 2.5% variance by Winpep. The Dynojet reader.
So you can multiple by .9759 to go from STD to SAE or 1.02467 to go from SAE to STD.
So at 600rwhp STD, you are making 585.54 SAE. I have seen a few that wanted to say they had 600rwhp but went to STD. What ever makes you sleep at night. The rest of the world uses SAE and typically 3-5 smoothing.
So you can multiple by .9759 to go from STD to SAE or 1.02467 to go from SAE to STD.
So at 600rwhp STD, you are making 585.54 SAE. I have seen a few that wanted to say they had 600rwhp but went to STD. What ever makes you sleep at night. The rest of the world uses SAE and typically 3-5 smoothing.
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how does boost calculate into those corrections? since boost makes its own atmosphere would they not be further off the mark than an n/a motor which has to work with the atmosphere at that altitude and correction?
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On The Tree
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From: Lakeville, MN
I am aware that the Dynojet software will allow you to log boost much like AFR, but I don't believe it's being used to create the correction factors. It would be interesting to see a boosted car spin the rollers, once with boost reference and once without. I suspect the CF's will come out the same.
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From some of my note taking on Cadillac Forums when I was recording dyno #'s.
Some owners asked for all 3 correction factors when dynoing their '09 & newer Cad CTS-V. HTH
Below are several examples showing how different correction factors affect the same dyno run readings. The 1st (jrcmlc) shows 3 different correction factors & the 2nd (ultimateendz) shows 3 different correction factors. The 3rd (caddy wagon) shows 2 different correction factors.
Only the SAE correction factor figures are listed above for these cars.
506-----491-----M6----unc----Dynojet------05-19-11-------in-------jrcmlc
508-----496-----M6----sae.----Dynojet------05-19-11-------in-------jrcmlc
519-----507-----M6----std-----Dynojet------05-19-11-------in-------jrcmlc
477-----466-----A6----sae-----Dynojet------12-27-11-------ny-------ultimateendz
492-----480-----A6----std-----Dynojet------12-27-11-------ny-------ultimateendz
501-----485-----A6----unc.----Dynojet------12-27-11-------ny-------ultimateendz
495-----486-----M6----sae-----Dynojet------05-13-11-------ar-------caddy wagon
505-----496-----M6----std-----Dynojet------05-13-11-------ar-------caddy wagon
Some owners asked for all 3 correction factors when dynoing their '09 & newer Cad CTS-V. HTH
Below are several examples showing how different correction factors affect the same dyno run readings. The 1st (jrcmlc) shows 3 different correction factors & the 2nd (ultimateendz) shows 3 different correction factors. The 3rd (caddy wagon) shows 2 different correction factors.
Only the SAE correction factor figures are listed above for these cars.
506-----491-----M6----unc----Dynojet------05-19-11-------in-------jrcmlc
508-----496-----M6----sae.----Dynojet------05-19-11-------in-------jrcmlc
519-----507-----M6----std-----Dynojet------05-19-11-------in-------jrcmlc
477-----466-----A6----sae-----Dynojet------12-27-11-------ny-------ultimateendz
492-----480-----A6----std-----Dynojet------12-27-11-------ny-------ultimateendz
501-----485-----A6----unc.----Dynojet------12-27-11-------ny-------ultimateendz
495-----486-----M6----sae-----Dynojet------05-13-11-------ar-------caddy wagon
505-----496-----M6----std-----Dynojet------05-13-11-------ar-------caddy wagon
