dyno results are in...

tmoss · Jul 20, 2004

94DreamGT said:
There ya have it folks...straight from the mouth of a fella who works at the company who makes the chasis dyno equipment. I'm tending to believe him.

Sorry Tom...looks like STD isn't what was "actually" made...it is just another correction factor that tends not to be used anymore. Look at any magazine, visit an event, or go to any shop...people use SAE. Only benefit I would see to stating STD numbers if they were higher than SAE and you're trying to overinflate your numbers. Like I said, my STD #'s were like 310/340...but no one uses that so its pointless to compare.

Please tell me why the better dyno shops have a weather station that puts correction factors in the dyno results directly. Ed Curtis brought this up in a previous post about dyno results. What is that "calibaration" factor?

You talked to guy who is a dyno rep - how do we know he's got the straight skinny? Just cause he works for the company doesn't impress or convince me. He didn't even discuss specific correction numbers with you (see below). Ever hear of a bad recommendation from the comp cams "tech" guys? I'm not being argumentative here, I'd like to get the right info out there too - look at the two SAE correction factors below.

The J607 specification uses a temperature of 60 F as “normal” compared to J1349 (or J1985) which used 77 F. If you use both systems with the same set of data you will get higher results for HP/TRQ with the J607. That means you cannot compare corrected data from the two different systems.

If STD is never used anymore, then why is it a cal factor in every dyno out there? MANY of the dyno graphs you see on these boards are sporting the STD cal factor (I have them saved as imagein a file I keep of dyno graphs), so there are quite a few shops using it - right or wrong.

Ed Curtis, Brian, Buddy Rawls - you out there? Shed any light on this for us?

tmoss · Jul 20, 2004

greg@berkeley said:
and if the word directly from dynojet weren't enough, let's think about this ourselves:
my SAE numbers were 334/309. on that day, the temp was in the mid 80s and it was pretty humid. therefore, my actual power would be lower than the corrected sae values (i think they are 70 degrees and dry air), right? well, my STD numbers 341/315. that alone proves that std numbers are not the actual numbers. in fact, my RAW numbers were 1 or 2 less than my SAE numbers.

This is puzzling to me Greg. If your in Berkley, your not at too high an elevation so the BP will have much less affect than the temp. If your dyno was done at 80* and high humidity, then correction to either 60* or 77* should have brought your raw numbers up, not down. Colder air makes more power holding other variables constant - right?

greg@berkeley · Jul 20, 2004

tmoss said:
This is puzzling to me Greg. If your in Berkley, your not at too high an elevation so the BP will have much less affect than the temp. If your dyno was done at 80* and high humidity, then correction to either 60* or 77* should have brought your raw numbers up, not down. Colder air makes more power holding other variables constant - right?

actually, the car was dynoed just out of the twin cities in minnesota. i don't know the elevation.

you didn't really make sense in that post. you are right that the corrections brought my numbers up. both my sae and std numbers were higher than my raw numbers. your logic is right, but you came to the wrong conclusion.

tmoss · Jul 20, 2004

greg@berkeley said:
and if the word directly from dynojet weren't enough, let's think about this ourselves:
my SAE numbers were 334/309. on that day, the temp was in the mid 80s and it was pretty humid. therefore, my actual power would be lower than the corrected sae values (i think they are 70 degrees and dry air), right? well, my STD numbers 341/315. that alone proves that std numbers are not the actual numbers. in fact, my RAW numbers were 1 or 2 less than my SAE numbers.

This is puzzling to me Greg. If your in Berkley, your not at too high an elevation so the BP will have much less affect than the temp for correction. If your dyno was done at 80* and high humidity, then correction to either 60* or 77* should have brought your SAE corrected RAW numbers up, not down. Colder air makes more power holding other variables constant - right?
That formula you got from the rep uses "intake air temp" - where does that come from? We don't hook up a temp probe on dyno day do we? If it uses air temp, then the SAE "standard" has no one set temperature.

greg@berkeley · Jul 20, 2004

tmoss said:
That formula you got from the rep uses "intake air temp" - where does that come from? We don't hook up a temp probe on dyno day do we? If it uses air temp, then the SAE "standard" has no one set temperature.

i'm assuming that actually is the room air temp since there is no other temp in the formula.

and it does have a standard!!!! that's why you have to input the actual temperature into the correction formula!!! to correct for the temp in the room!!!

Grn92LX · Jul 20, 2004

tmoss said:
Please tell me why the better dyno shops have a weather station that puts correction factors in the dyno results directly. Ed Curtis brought this up in a previous post about dyno results. What is that "calibaration" factor?

You talked to guy who is a dyno rep - how do we know he's got the straight skinny? Just cause he works for the company doesn't impress or convince me. He didn't even discuss specific correction numbers with you (see below). Ever hear of a bad recommendation from the comp cams "tech" guys? I'm not being argumentative here, I'd like to get the right info out there too - look at the two SAE correction factors below.

The J607 specification uses a temperature of 60 F as “normal” compared to J1349 (or J1985) which used 77 F. If you use both systems with the same set of data you will get higher results for HP/TRQ with the J607. That means you cannot compare corrected data from the two different systems.

If STD is never used anymore, then why is it a cal factor in every dyno out there? MANY of the dyno graphs you see on these boards are sporting the STD cal factor (I have them saved as imagein a file I keep of dyno graphs), so there are quite a few shops using it - right or wrong.

Ed Curtis, Brian, Buddy Rawls - you out there? Shed any light on this for us?

Ding ding ding!! I was going to say that too about the "tech guy" over the phone. I've used 2 dyno's here in NY and BOTH used std numbers. One shop asked me which I wanted and I told him std.

tmoss · Jul 20, 2004

greg@berkeley said:
..... therefore, my actual power would be lower than the corrected sae values (i think they are 70 degrees and dry air), right? ...

I thought the SAE correction used one of the factors I listed (60* or 77*) - you seem to agree here, but the formula given by the "rep" states that the correction will float with the temperature. It can't be both unless one is for STD (or some other factor) and the other is for SAE. For any one given track or dyno location, BP will have much less affect on correction than temperature.

tmoss · Jul 20, 2004

greg@berkeley said:
you didn't really make sense in that post. you are right that the corrections brought my numbers up. both my sae and std numbers were higher than my raw numbers. your logic is right, but you came to the wrong conclusion.

Brain fart.........

greg@berkeley · Jul 20, 2004

tmoss said:
I thought the SAE correction used one of the factors I listed (60* or 77*) - you seem to agree here, but the formula given by the "rep" states that the correction will float with the temperature...

of course. the correction factor is dependant on the temperature. the higher the ambient air temperature, the higher the correction factor.

greg@berkeley · Jul 20, 2004

CF=1.18*29.22/BDO*TO+460/537-0.18

now that i took a second look at that formula, i think the dynojet dude may have read it incorrectly.
the 29.22 means 29.22 mmHg.
460 corresponds to 0 degrees fahrenheit which is equivalent to 460 rankine (other temp scale).
537 corresponds to 77 degrees fahrenheit (537-460=77).

i think the formula should read something more like

CF=1.18*29.22/BDO*(TO+460)/537-0.18

that way, if the pressure were higher, the correction factor would be lower, and if the temperature were higher, the correction factor would be higher.

so tom, you are right about the 77 degrees standard. also, 29.22 mmHg is standard, and zero humidity is standard.

make more sense now?

tmoss · Jul 20, 2004

Now that makes sense since the actual temp is used to modify the reference temp.

Now, I still wonder about STD.

dyno results are in...

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