DynoJet runs, SAE versus Standard correction
 

Seen a number of post again lately (which seem to come up again every few years) talking about the differences in DynoJet RWHP figures when using SAE versus Standard correction......well, here they are :D

Same run file from my car, using SAE, Standard, then "inflating" the numbers by using Standard and smoothing 0.

First, SAE correction and Smoothing 5.....
https://cimg1.ibsrv.net/gimg/www.cor...74d98047a4.jpg

Runtime conditions on the dyno that day...
https://cimg2.ibsrv.net/gimg/www.cor...c481c8545f.jpg


correction factor using Standard....
https://cimg3.ibsrv.net/gimg/www.cor...391f900786.jpg


Finally, Standard correction with Smoothing set to 0.... magically picking up 15 RWHP and 10 ft/lbs of torque
https://cimg4.ibsrv.net/gimg/www.cor...b22ff0ce25.jpg

Keep in mind that even dyno files don't show the whole picture, as ECT, knock retard, et al, play a part in this too. You'd need the data log file from the run (HP Tuner, EFI, et al) to go along with the dyno files to see a more complete picture :)

Thanks for posting. I don't really consider dyno numbers valid unless they are SAE smoothing 5. I am sure that this thread is going to be very popular today. Happy Friday. :cheers:

The difference is usually 2-3% but I have seen more or less, depending on the conditions. I have never messed around with the smoothing. I didn't know it would have that effect. It makes sense though. Smoothing out the small peaks and dips will definitely show lesser power.

Great post... High HP numbers are great but, Real performance are found out in Mexico or at the track.

STD isn't corrected, it's what the car did that day in those conditions.

SAE smoothing 5 is basically the settings that every platform uses, which allows some consistency with numbers on different dynos, cars, etc..

I think you meant to say UNCORRECTED is what the car did that day in those conditions.

Standard correction factor is still a number that has adjustments made to the final number, just a bit more optimistic values are used versus the SAE factor, which is the industry standard used by the manufactures nowadays :thumbs:

FYI, my UNCORRECTED numbers were 576 RWHP...or more specifically, the TRUE RWHP my car makes in Phoenix, AZ at altitude.
The correction factor was 4% (correction factor 1.04) :cheers:

This is also why I chuckle when people use trap speeds to validate the dyno numbers. Make no mistake, while I may make "600 RWHP" using the most conservative numbers for showing the power of my engine, it will "trap" MPH consistent with what a 576 RWHP car would run here at altitude in Phoenix, AZ.


https://cimg0.ibsrv.net/gimg/www.cor...e7987471f8.jpg

Uncorrected DynoJet dyno numbers with Smoothing set to 5. 576 RWHP/490 TQ

SAE is the manufacture's standard for advertising the rated HP for your engine....... the LS7 is rated/advertised as 505 crank HP, SAE corrected :thumbs:

Smoothing 5 removes the spikes (or noise, if you prefer) in the measured signals coming from the spark leads. It averages the highs and lows to display a "smoother" graph.

SAE correction corrects to 77* F, 29.23inhg and 0% humidity.



STD corrects to 62*F 29.92inhg and 0% humidity.




The correction factor is what applying these does to your actual conditions during the run. Around here we are in the 70-80 degree range at sea level with low humidity so regardless of correction type the CF tends to float between .98-1.02.

Someone in Denver during the summer for example may see a CF of 1.2 or more ( meaning the correction factor is adding 20%+ to try and simulate numbers in the conditions specified.


At the end of the day its a tuning tool and not something where you race dyno sheets. Trap speed tells the true story as there is no correction factor out on the road, the car runs uncorrected.

I should post some DIN numbers. That would cause all kinds of chaos around here lol

^This. :thumbs:


The old school mustang dyno settings read low like a dyno dynamics. Some of these older machines were given a new calibration factor to provide more dynojet like numbers. Now some mustangs read high, some read like a dynojet, and some read low. Its very inconsistent and hard to compare to other shops. However, they are a great tuning tool.

DIN correction was almost identical to Standard correction :thumbs:

Great post, particularly the info about smoothing! Thanks! :cheers:

Great thread indeed. :thumbs:
Now throw in different drivers at the same track and see how trap speed can vary. :eek:

Put a cup of coffee near the thermocouple and watch the HP increase. :lol:
There's a youtube video showing the difference between 2 pulls with the second one having two extra clicks on the rear hold down straps. :toetap:

The bottom line it's a tuning tool. You can't race dyno sheets as much as the guys at the car shows would like you to believe.

Great thread. My points exactly. All these Disney Dynos and crazy alogrylims and calculations.

The standard for 20 years have been Dyno Jets and SAE and even know they are consistant from dyno to dyno, there are some who's weather stations may be placed on more or less ventilated areas, calibrated differently etc.

For me, if you are going to compare power numbers they have to be from the same stardard that in theory ahoild be within 10rw with eachother if calibrations are similar.

All these dynos: Mustang, Dyna Pack, Super Flow, etc. They all produce a diferent standard so you cant compare numbers among each other you will have to baseline with a Dyno Jet.

Now, if you do all your mods and tunning on one type, any dyno is a good for documenting changes.

IMHO, the best dyno for Tunning purposes is the Super Flow wheel dyno but they are far and few and more dificult to find.

For "standarized" power numbers, the Dyno Jet is the end all.

My .02