SAE Vs. STD Comparison Thread
01-27-2009, 09:02 PM
#21
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it depends on the atmospheric conditions during the dyno run... SAE is a standard pressure, temperature, and relative humidity. so the farther your actual conditions deviate from these standard conditions the more your numbers will deviate in STD form versus SAE...
01-28-2009, 09:58 AM
#23
I don't think it's that simple. There are far too many variables at the track to find consistent results from a given setup. The dyno simplifies this process as all you have to do is spin the rollers. The use of correction factors create an even more level playing field when it comes to comparing setups and finding consistency. If somoeone went to the track in 2000 DA then changed their setup and went back to the track in -2000 DA, then said they gained from the changes how would you know if the gains were from the changes or DA? You'd have to use some sort of calculation to figure out the gains from DA then look at it apples to apples. The dyno with correction factors allows you to determine relative power between setups and that's all. It takes more that just power to get down the track right? That's the point here, using correction factors to keep things apples to apples and eliminate as many variables as possible.
01-28-2009, 10:07 AM
#24
In reguards to the correction factors, whatever you use is what you use. Some people just want their car to put out more power, so that's what you give them.
Kaltech is dead on with the 4% more for correction between the two.
Another thing that I have noticed in my years of testing is the farther you get away from 1 on the correction factor scale. The harder it is to repeat. When were dynoing at Katech, we would notice a difference in power from days where there was a 2% SAE correction to days when it was 6% or higher. It seems the corrections start to get outside their limits once you get above SAE J1349>5% and SAE J-607, a.k.a. STP>9%.
I guess I am with the others on here and agree you can't race dyno numbers. Yes they tel you a number, but there are so many variables with those numbers, the only thing you can really do is see changes that day. Yes, you can keep running the day after day, but a new baseline needs to be established each and every day you make a run.
And then if the weather turns suddenly during the testing, you need to re-baseline. I know here in MN, it could be 80 deg. with 90% Humidity and then an hour later it will be 50 deg. with 45% humidity. If you don't rebaseline, you may see positive changes when they really aren't.
Just my 2 cents.
Kaltech is dead on with the 4% more for correction between the two.
Another thing that I have noticed in my years of testing is the farther you get away from 1 on the correction factor scale. The harder it is to repeat. When were dynoing at Katech, we would notice a difference in power from days where there was a 2% SAE correction to days when it was 6% or higher. It seems the corrections start to get outside their limits once you get above SAE J1349>5% and SAE J-607, a.k.a. STP>9%.
I guess I am with the others on here and agree you can't race dyno numbers. Yes they tel you a number, but there are so many variables with those numbers, the only thing you can really do is see changes that day. Yes, you can keep running the day after day, but a new baseline needs to be established each and every day you make a run.
And then if the weather turns suddenly during the testing, you need to re-baseline. I know here in MN, it could be 80 deg. with 90% Humidity and then an hour later it will be 50 deg. with 45% humidity. If you don't rebaseline, you may see positive changes when they really aren't.
Just my 2 cents.
01-28-2009, 11:36 AM
#25
The problem with that, using uncorrected timeslips and corrected dyno readings, is that you can have the same power (as verified by a dyno) and have two time slips from different parts of the day (I have seen the DA at our tracks go from -1000 at 9am to +2000 by noon) and they can be around .3 tenths off or 3 MPH off (for a deadly consistent setup). If you use corrected data, use it across the board for all you testing. Do not mix corrected (dyno) data with uncorrected (track) data. Since no one wants to correct their -4000 DA runs to SAE standard, and since no one holds any value to uncorrected dyno results, the SAE dyno readings will have no bearing on uncorrected track results or improvements. That is just my $0.02.
To reference your example what if someone changed their tune at the track and the DA swung 3000 like you stated. Did the tune find the .3 and 3 mph or DA. Harder to control and figure out. Every dyno has correction ability but not many people bring weather stations to the track.
Trust me I'm COMPLETELY for track results over dyno numbers but I think the nature of this thread was referring to using dyno results to market products. The fact is dyno numbers are far more available and easy to obtain in order to reference parts purchases than time slips are.
01-28-2009, 11:59 AM
#26
Pretty much everyone wants the highest dyno sheet they can get to post up. Facts of life here.
A big thing up here is dynoing in the dead cold winter.The #'s are always higher corrected or not.On a 900hp car we've seen a 100rwhp swing between SAE and Uncorrected.
A big thing up here is dynoing in the dead cold winter.The #'s are always higher corrected or not.On a 900hp car we've seen a 100rwhp swing between SAE and Uncorrected.
01-28-2009, 04:15 PM
#27
I understand what you're saying and totally agree with you. Sadly it's an imperfect science when trying to completely tie dyno numbers and track times together. I just feel that if you're doing a to b parts comparisons there are a lot less variables on the dyno than at the track. Shop weather won't have DA swings like the track will. All I'm really saying in this thread is that you can't do a to b parts comparisons and have a showing sae numbers than b showing uncorrected because the weather was favorable to claim gains. There are enough examples posted already to show the differences the dyno will show from sae to uncorrected. Marketing is fine but falsifying claims because weather is in your favor is shady.
To reference your example what if someone changed their tune at the track and the DA swung 3000 like you stated. Did the tune find the .3 and 3 mph or DA. Harder to control and figure out. Every dyno has correction ability but not many people bring weather stations to the track.
Trust me I'm COMPLETELY for track results over dyno numbers but I think the nature of this thread was referring to using dyno results to market products. The fact is dyno numbers are far more available and easy to obtain in order to reference parts purchases than time slips are.
To reference your example what if someone changed their tune at the track and the DA swung 3000 like you stated. Did the tune find the .3 and 3 mph or DA. Harder to control and figure out. Every dyno has correction ability but not many people bring weather stations to the track.
Trust me I'm COMPLETELY for track results over dyno numbers but I think the nature of this thread was referring to using dyno results to market products. The fact is dyno numbers are far more available and easy to obtain in order to reference parts purchases than time slips are.
So long as the customer understands it is the delta that really matters, not the absolute number. This is why I try not to comment on posts asking "If I have 400hp how fast should it be?" or "With 400hp you should be low 11s", it doesn't work that way. The sad thing is that different dyno also measure power differently and such report higher or lower numbers. Seems that the DynoJet has become the internet standard. I see some shops alter their readings to local dynojet or dynapack numbers.
01-29-2009, 08:31 AM
#28
Just so you know and we are clear, I completely agree with you regarding using SAE numbers for marketing reasons. So long as the customer understands it is the delta that really matters, not the absolute number. This is why I try not to comment on posts asking "If I have 400hp how fast should it be?" or "With 400hp you should be low 11s", it doesn't work that way. The sad thing is that different dyno also measure power differently and such report higher or lower numbers. Seems that the DynoJet has become the internet standard. I see some shops alter their readings to local dynojet or dynapack numbers.
So long as the customer understands it is the delta that really matters, not the absolute number. This is why I try not to comment on posts asking "If I have 400hp how fast should it be?" or "With 400hp you should be low 11s", it doesn't work that way. The sad thing is that different dyno also measure power differently and such report higher or lower numbers. Seems that the DynoJet has become the internet standard. I see some shops alter their readings to local dynojet or dynapack numbers.