InfrareV

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.

Goosecaddy05

ask Vengeance racing, all their numbers are on STD correction

InfrareV

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.

Ron@Vengeance

iTrader: (51)

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.

hrcslam

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.

Goosecaddy05

That is what i got from David, i was wondering about that since most people use SAE, thanks for clearing it up Ron I guess he was mistaken?

InfrareV

Noted and fixed. I don't intend to advertise it, I'll just point to it when SAE vs STD questions come up. That said anyone who finds it is welcome to use it.

hrcslam

Cool man, cool calculator too. I'll definitely use it too. Thanks!

NW Iowa WS6

iTrader: (9)

Take your STD numbers times .98 to convert to SAE, not perfect but pretty damn close most of the time

RAMPANT

iTrader: (17)

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.

InfrareV

Correct, not perfect but pretty good. That will work if you're trying to do some quick math in a parking lot, but the calculator is more accurate then that.

Your math is only correct for that one run. The relationship between SAE and STD isn't linear. If you look at multiple files you'll see that .9759 isn't accurate. I've put 10 files into my calculator, it's only off been off by a few hundredths for DIN, SAE, STD, and Uncorrected.

Goosecaddy05

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?

InfrareV

It doesn't, at least not with regards to dyno results(atleast to my knowledge). As far as I know Dynojet's software isn't accomodating boost and neither is this calculator. That's not to say it shouldn't, perhaps it should but that's a bit over my head.

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.

Gary Wells

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

leftysrepsol

iTrader: (3)

Wow, and to think the first thing I thought of when I saw the title of this tread was Sexually Transmitted Disease Correction Factor

Gary Wells

That particular correction factor would not be turning the rubber inside out & using it again.