A couple dyno terminology questions

[V10SpeedLuvr]

This may be a dumb question, but there are no dumb questions, only dumb people (and i qualify )

I dynoed my car Saturday and on my printout it says "CF: SAE Smoothing: 5" and "SAE 1.03"

I know "SAE Smoothing: 5" gives the highest readout #'s and dyno #'s can be SAE corrected for weather temperatures. My questions are what do these terms (SAE and SAE Smoothing) mean and are my #'s already SAE corrected for the weather (90.19 degrees, 32% humidity) or is there some calculation I can do to find the SAE corrected #'s? My results were 370.59 RWHP, 450.47 RWTQ

 

[Chuck 98 RT/10]

It means your Viper has those ugly yellow wheels.

 

[V10SpeedLuvr]

It means your Viper has those ugly yellow wheels.

That's because I pointed out that you said you liked Gen 1 chrome wheels earlier isn't it?

 

[ViperRichRT10]

It means your Viper has those ugly yellow wheels.

LOL!!! Chuck, that was great! But those wheels are good for 25 RWHP on SAE corrections for "smoothness"!

 

[kcobean]

If you've ever seen a dyno chart printed with no SAE smoothing, it's very jagged. My understanding of the smoothing factor is that it's applied to make the curve look like a curve rather than a man having a serious heart episode. The higher the number, the more the software removes "irregularities" in the curve and turns it into a smooth line.

The SAE 1.03 number indicates the correction factor applied to the raw numbers. I'm not positive how it's calculated. Out of curiousity, do you have your raw numbers, and what were the temp/pressure when you dynoed?

 

[V10SpeedLuvr]

Out of curiousity, do you have your raw numbers, and what were the temp/pressure when you dynoed?

The #'s on the printout are:

90.19 degrees, 32% humidity, 29.27 in-Hg. My results were 370.59 RWHP, 450.47 RWTQ. Not sure if those are raw or SAE corrected.

 

[Dave T (BADVENM)]

I believe the dyno software uses barometric pressure as one of its parameters as well as temperature and humidity. This is whats needed to adjust the numbers to sea level which makes a level playing field (of sorts) when comparing numbers against other numbers (dyno's being equal which we know they arent).

As far as your dyno numbers, if those are at the wheels (which it would appear) I believe the driveline adjustment is 12-15%? So, multiply 370.59x13.5% (for a lack of a better number right now) and you get 420rwhp at the crank. I think the stock hp numbers are 400 for gen I's...correct? if so, your numbers are right on target.

It will also depend on if its a Mustang or Dynojet dynomometer. Mustang dyno's typically read lower then Dynojets. Theres lots of articles on the internet about the different dyno's and what makes them different.

 

[V10SpeedLuvr]

As far as your dyno numbers, if those are at the wheels (which it would appear) I believe the driveline adjustment is 12-15%? So, multiply 370.59x13.5% (for a lack of a better number right now) and you get 420rwhp at the crank. I think the stock hp numbers are 400 for gen I's...correct? if so, your numbers are right on target.

Yes, those are "at the wheels" #'s. I have a Gen 1.5, so I have 415HP at the crank

It will also depend on if its a Mustang or Dynojet dynomometer. Mustang dyno's typically read lower then Dynojets. Theres lots of articles on the internet about the different dyno's and what makes them different.

It was a Dynojet dyno

 

[kcobean]

Out of curiousity, do you have your raw numbers, and what were the temp/pressure when you dynoed?

The #'s on the printout are:

90.19 degrees, 32% humidity, 29.27 in-Hg. My results were 370.59 RWHP, 450.47 RWTQ. Not sure if those are raw or SAE corrected.

If the correction factor is listed, then they are corrected numbers. Because of the heat and humidity, your raw numbers are lower than they would be at the SAE standard temp/humidity/pressure...thus, your raw numbers are multiplied by 1.03 for correction. Not too big of an adjustment, but it's there.

 

[kcobean]

As far as your dyno numbers, if those are at the wheels (which it would appear) I believe the driveline adjustment is 12-15%? So, multiply 370.59x13.5% (for a lack of a better number right now) and you get 420rwhp at the crank. I think the stock hp numbers are 400 for gen I's...correct? if so, your numbers are right on target.

The equation doesn't quite work like that.

If you pulled 370.6 at the wheels and assume a 15% loss, that's 436 Crank HP (436 x .85 = 370.6) I'd say you're lookin' good considering that the 1996 RT/10 engine was factory rated at 415 BHP (according to the "features page" on this site.)

 

[Joseph Dell]

the SAE 1.03 means that based on barometric pressure, temp, and all the other things that the dyno measures, it took your raw numbers and multiplied them by 1.03 to get the number it shows you. ideal conditions are *** (i forget what... something like 76 degrees, low humidity, etc...). so when it is hotter out, the cars have a higher correction factor. if it is cooler out, you might actually see a reduction!

As for the smoothing, it is to make the lines less jagged. smoothing usually REMOVES peaks so the dyno numbers go down .1-1.5 total. it doesn't usually make it higher, i don't think.

get the dyno operator (if a dynojet) to e-mail you the RAW dyno file. then you can go to the dynojet web site and download the WINPEP software. they have a viewer that lets you view EXACTLY the same thing the dyno operator does. plus, it'll show you all the correction factors and let you play/manipulate the view. it doesn't let you modify the data (so you can't make a fake dyno graph) but it lets you see ALL the data points that the dyno shared.

good luck!

JD

 

[V10SpeedLuvr]

Thanks guys. Great explanations. I'll email the dyno company and try to get the raw #'s so I can play with them like JD recommended. I knew there was a standard 12-15% driveline loss on HP, but is it the same for torque or are the % numbers different?

 

[kcobean]

Since HP is just a calculation of torque over time, the correction factor should be the same.

Horsepower is calculated like this:

HP = (torque x RPM) / 5252.

If you look on your dyno chart, you'll notice that 5252 RPM is where your torque and HP curves meet.