100% Humidity
TECH Enthusiast
Joined: Sep 2004
Posts: 564
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From: Omaha, NE
Originally Posted by nastyta
Im saying this bc I went to the dyno and my numbers seemed kinda low only thing i could see wrong was the day of the dyno it was 100% humidity....?
If they were operating the dyno properly, they would have compensated for that in your dyno #s because they should be using an SAE atmospheric correction factor. If they were not, you got ripped.
I was kinds thinking the same thing, I have a 408 10.1 comp. I thought it would dyno higher than what it did I'll take it back to them..and see if we caint solve this problem thanks for ur help !
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Originally Posted by dynocar
If they were operating the dyno properly, they would have compensated for that in your dyno #s because they should be using an SAE atmospheric correction factor. If they were not, you got ripped.
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Yeah... Corrections " TRY " to compensate the best they can but cannot overcome major weather conditions all the time. It is still best to try and dyno as close as you can to the same baseline conditions as much as possible.
BTW.. I try to not do and dyno runs at 100% humitity if at all possible. I realize a very dyno busy shop cannot do this but around here we can work around it alot of times.
BTW.. I try to not do and dyno runs at 100% humitity if at all possible. I realize a very dyno busy shop cannot do this but around here we can work around it alot of times.
FormerVendor
Joined: Jan 2002
Posts: 173
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From: Mpls., MN
Originally Posted by Beast96Z
Even with the correction, the numbers are still lower. Less oxegyn in a givin space will make for less power, corrected or not. Go back and dyno on the same dyno on a 50* day with 10% humidity and your numbers will go up a good bit.
Brian
HiTech Motorsport
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Joined: Sep 2004
Posts: 564
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From: Omaha, NE
Originally Posted by DynoDR
Yeah... Corrections " TRY " to compensate the best they can but cannot overcome major weather conditions all the time. It is still best to try and dyno as close as you can to the same baseline conditions as much as possible.
BTW.. I try to not do and dyno runs at 100% humitity if at all possible. I realize a very dyno busy shop cannot do this but around here we can work around it alot of times.
BTW.. I try to not do and dyno runs at 100% humitity if at all possible. I realize a very dyno busy shop cannot do this but around here we can work around it alot of times.
With NA cars I have found the correction factors to be very accurate from one weather extreme to the other. On FI cars this is not the case because such cars make their own atmosphere with the outside atmospheric changes not having as much of an affect. If I wanted high numbers on an FI car I would choose a day with the largest correction factor.
I guess I should have been clear on those "extreme" days, the ones that show a 9%-10% correction or more. They still may get close but wasnt there a max of around a 7% correction that SAE allowed for.
Still, always better to try to be consistent with as many conditions as possible. Good point of bringing up the FI example dynocar.
Still, always better to try to be consistent with as many conditions as possible. Good point of bringing up the FI example dynocar.
FormerVendor
Joined: Jan 2002
Posts: 173
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From: Mpls., MN
Originally Posted by dynocar
With NA cars I have found the correction factors to be very accurate from one weather extreme to the other. On FI cars this is not the case because such cars make their own atmosphere with the outside atmospheric changes not having as much of an affect.
Brian
HiTech Motorsport
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Joined: Sep 2004
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From: Omaha, NE
DynoDR, no there is not an SAE limit of 7%, we have seen 12+% correction here at 1000 ft on certain hot/humid summer days and at higher elevations such as CO, I'm sure they see much higher.
HTMtrSpt, my post was stating what I've observed on the dyno using a given SAE correction standard. We used the J607 for our first approx 5 years and the J1349 for the past approx 10 yrs. Interesting, I did not realize that there are different corr factors for forced induction, can you give me more info, such as an example.
HTMtrSpt, my post was stating what I've observed on the dyno using a given SAE correction standard. We used the J607 for our first approx 5 years and the J1349 for the past approx 10 yrs. Interesting, I did not realize that there are different corr factors for forced induction, can you give me more info, such as an example.
Originally Posted by HTMtrSprt
You seem to be missing the whole point of the correction factor.
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Joined: Sep 2004
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From: Omaha, NE
Originally Posted by Beast96Z
No, I know what it's for. Wether or not it works to the full extent is another question. We have extreme humidity here in the south, and cars always seem to dyno lower in those conditions. Now operator error is a diffrent story. There's no one person sitting at the desk monitoring atmospheric conditions, so I can only assume that they are using a "standard" correction factor. I was unaware that you could actually go in and change the %.
Like I stated previously, it seems to work extremely well for NA applications for us anyway. We live in a part of the country that has very extreme swings -20 to 105 deg F, very low to very high humity, etc, yet we can usually directly overlay a vehicles power curves whether it was dynoed in the middle of winter or summer. Some dynos have an automatic weather station build in monitoring the conditions that automatically set the factors in the dynos computer. We have a manual, independent system which I personnally prefer because we can easily move it to the proximity of the engine's induction, whether it's a front or rear engine car and also keep it away from the radiant heater in the winter months. It also forces the dyno operator to monitor each weather condition for decisions as to how ragged edged we want to go on the tune. If a dyno operator does not constantly monitor a manual system during a dyno session, it will deffinately skew the readings. The shop's atmospheric conditions can change dramatically after a few pulls.
Hey guys thanks for your input if somebody would like to pm me, I would like to explain my problem in detail if ...ne body has the time to talk..thanks again guys !
I realize that you may come up with a correction of 10-12% or more but what I am saying is if you are testing to SAE standards then any correction factor over a certain amount, and by memory I think it is 6, maybe 7% , cannot or should not be used. I know it usually is pretty much dead on, but you are leaving ALOT of to a correction multiplier when you get up to 10% or more.
Just saying again, the less varibles between different test the better.
Just saying again, the less varibles between different test the better.
Originally Posted by dynocar
DynoDR, no there is not an SAE limit of 7%, we have seen 12+% correction here at 1000 ft on certain hot/humid summer days and at higher elevations such as CO, I'm sure they see much higher.
HTMtrSpt, my post was stating what I've observed on the dyno using a given SAE correction standard. We used the J607 for our first approx 5 years and the J1349 for the past approx 10 yrs. Interesting, I did not realize that there are different corr factors for forced induction, can you give me more info, such as an example.
HTMtrSpt, my post was stating what I've observed on the dyno using a given SAE correction standard. We used the J607 for our first approx 5 years and the J1349 for the past approx 10 yrs. Interesting, I did not realize that there are different corr factors for forced induction, can you give me more info, such as an example.
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Joined: Sep 2004
Posts: 564
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From: Omaha, NE
Originally Posted by DynoDR
I realize that you may come up with a correction of 10-12% or more but what I am saying is if you are testing to SAE standards then any correction factor over a certain amount, and by memory I think it is 6, maybe 7% , cannot or should not be used. I know it usually is pretty much dead on, but you are leaving ALOT of to a correction multiplier when you get up to 10% or more.
Just saying again, the less varibles between different test the better.
Just saying again, the less varibles between different test the better.