So, in another thread, I promised that I would post up the excel sheet I'm using to calculate torque and power output from HP Tuners. So, here it is.
Now, there are some important items to note in order to use this successfully.
What you need: You will need HP Tuners to scan an acceleration run in a certain gear. You will also need to log the "Transmission Output Speed" PID. This is important because it gives much higher resolution values (0.1 RPM's) than the wheelspeed PID's and it is not as erratic as the engine RPM values. You will also need Excel to open this program.
How it Works: At the most basic level, this spreadsheet works much like an inertial dyno. Only instead of using a rotational inertia, it uses your vehicle mass as the inertia. It does this by converting the Transmission Output RPM into a vehicle speed. Then, the rate of change of vehicle speed is calculated which in turn is an acceleration value. This acceleration can be used to find the torque at the wheels and thus, at the engine.
How Drag is Accounted For: The two major forms of drag are accounted for. Rolling resistance is taken into account using a rolling resistance correlation developed by the Institute of Technology in Stuttgart. This is based upon vehicle speed to the 5/2 power along with coefficients for different tire pressures. Aero drag is taken into account using the standard Coefficient of Drag and frontal area relation.
Important Notes:
1) This program will output your true uncorrected rear wheel torque and horsepower. If your run is done in weather semi close to sea level and around 70*F, then you will be within a few percent of SAE corrected values. However, depending on atmospheric conditions, the SAE correction factor could significant (you should always use SAE values regardless).
2) For these accleration runs to be compared to a dyno, the runs must be in 4th gear (yeah, its fun getting the data!). This is because there are two major factors that affect how power makes it to the rear wheels. There is an efficiency factor that takes into account the heat lost due to friction and viscous forces, but there is also another usually ignored factor. Inertial losses. Runs in lower gears accelerate the driveline faster causing higher inertial losses. This effect is not insignificant and can be seen in the below graph. These were torque/power measurements I took for each gear all within a few minutes of one another on my car.
3) Be very careful with the timestep you enter. The time output in HP Tunes is rather erratic and thus you have to use the average frames per second (trust me, it works much better this way). I have provided a series of columns on the 2nd sheet that let you make sure your time step is correct. I left a comment on that cell that should give you an idea of values to try.
4) I have not tried this with an A4 car. Obviously, the gear ratios will be off, but even if these are changed, I'm not sure how it will work as the whole torque converter really screws things up.
I will be updating this and posting it as new versions if there are any errors or as I try to add new features. I already realize I need to add spot to input the SAE correction factor so that a corrected graph is automatically generated. Let me know if there are any problems.
Btw, in case anybody is wondering, ShoddyHog's 4th gear pull makes up the default values.
Please, if you use this, post up your results as I would like to see how it works for others.
Hope some people can find this useful.
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2006 M6 GTO - 333hp/323tq stock
Kook's Sig. Series LT's, Catless Mids, Magnaflow Catback, Ported Intake, Vararam, HP Tuners & Wideband - 377 hp/386 tq.
It should also be noted that these graphs were done on a version of the sheet previous to the one posted here. In the older version, I was using a much simpler rolling resistance equation.
how are you accounting for noise in the data and imprecisions stemming from limited resolution of some of the data we get? I've done all this before but it's all fallen short of useful due to lack of resolution.
curious how much space you left for sample size fsae....
reason i ask is, a simple way to increase sample rate would be a trimed down hpt config....
since most people run hpt interfaces with 24+ bits being logged... trimming it down to say 6 should increase the sample rate some what significantly... but only useful if there is space for a sample that large/ room to exand your calculation to cover the increased resolution
havent looked at your sheet yet, so not sure what all you did yet ....
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2004 Quicksilver GTO A4
Stuff, with some Stuff, and a little extra stuff...
422/412 www.zombo.com
how are you accounting for noise in the data and imprecisions stemming from limited resolution of some of the data we get? I've done all this before but it's all fallen short of useful due to lack of resolution.
Ah, Marcin, I was curious if you'd show up. I've followed your posts over on the HPtuners forum. I love your website as well.
Well, I've tried pretty much every PID available that can somehow display wheelspeed. The speed PID's are worthless because their resolution is only the nearest mph. I originally tried engine RPM with limited success. This could get me in the ballpark for average numbers, but the data was too noisy. There are instances where the recorded RPM will not change in between data points which can cause problems as I'm sure you can imagine.
One day, I found Transmission output RPM. I decided to log it and was pleasantly surprised that it at least had better resolution and appeared more accurate than the other options available. I'm only logging at 10 frames per second and it gives me plenty of samples to smooth. I am not a data analysis engineer so I am not using any crazing data reduction, least squares fits or anything. I am just using a simple moving average. This smooths the data well enough to give the graphs posted above.
There are issues with this method if you are looking for extremely precise values, but for just a dyno graph with maximum's for torque and power, this seems to work fine.
If you have any suggestions I would be all ears.
Quote:
Originally Posted by GoatKart...
curious how much space you left for sample size fsae....
reason i ask is, a simple way to increase sample rate would be a trimed down hpt config....
since most people run hpt interfaces with 24+ bits being logged... trimming it down to say 6 should increase the sample rate some what significantly... but only useful if there is space for a sample that large/ room to exand your calculation to cover the increased resolution
havent looked at your sheet yet, so not sure what all you did yet ....
Yes, this sheet should work with any logging rate as there is an input for the logging frequency. All the above graphs are done at 10 samples per second and yield results good enough to satisfy myself.
I made my runs this morning. I did three pulls from about 1000 RPM to redline. That's a hell of a ride She's VERY lean down there, so don't look for me to be doing this again. Hell, I didn't even know if I had it in me to lug her that bad.
I'd just looked at the spreadsheet quickly the other day, and thought there would be entry for atomospheric conditions. Am I missing them, or is there something else I need to do besides the brown cells and the log data? I'll be working on one of the runs and uploading everything here for you to check out. I've also recorded the weather conditions...and have video, of course.
I'll attach the runs, but I'm not going to have time to mess with it this morning. I've also got a little vid upoading.
Conditions:
Temp: 58 f
Humidity: 76%
Dew point: 51 f
Barometric pressure: 29.91
Elevation: ~700'
Fuel: 8 gallons
Driver: 240 lbs (and very handsome)
I exported my data to .csv, then opened it with Excel. I then deleted all the rows until I had just my WOT run in there, then I highlighted the row for Trans Output RPM and pasted it in. It changed the numbers to the right, so it did calculate. The only problem is that the calculations don't extend down far enough because I have more data points than the baseline run.
I then tried to copy in the time column. It has the same problem, and it also didn't seem to calculate the "calculated time" column. I tried cut & paste, and I also tried paste special > values, but neither seemed to work.
FWIW, I'm a database applicaiton programmer, and would rather slam my penis in my car door than use Excel. Just thought you should know
This is pretty damn cool. I did have time to go back and figure it out with a little of your help. Thanks!
I'll have to work the other two runs tomorrow, but I find the results very interesting. Not only does the graph closely follow my real dyno sheets, the low RPM curve matches exactly what I feel in the car.
Thanks again for this toy Edit: I still hate Excel. Just sayin'.
Gerry
Last edited by ShoddyHog : 11-08-2009 at 07:41 PM.
This is pretty damn cool. I did have time to go back and figure it out with a little of your help. Thanks!
I'll have to work the other two runs tomorrow, but I find the results very interesting. Not only does the graph closely follow my real dyno sheets, the low RPM curve matches exactly what I feel in the car.
Thanks again for this toy Edit: I still hate Excel. Just sayin'.
Gerry
Wait, this is blasphemy. You have a healthy sized cam and heads and you are still making 300 ft-lbs at 1500 RPM. Haha.
I'm excited to see this as I ended up going with just a barely larger cam from Ed (step above the tigershark). I am impressed with the super low end torque.
It's funny because I'm sure the database stuff you deal with would give me nightmares. I'm just a mechanical guy, so I like the 'point and click' programming of excel.
Wait, this is blasphemy. You have a healthy sized cam and heads and you are still making 300 ft-lbs at 1500 RPM. Haha.
Yeah, that does go against what they say, doesn't it? I'd have to go back and search, but I'm almost positve that I was asked how much "bottom end torque" I lost by installing the cam, and my respoonse was that I felt I picked up some or at least didn't lose any.
The graph is interesting to me too because if I nail it from a low RPM (in a lower gear) and she hooks, I can really feel the cam come alive at about 2500 RPM. If you listen to the video, I think you can even hear it.
Pretty slick. I will try to run the other two tonight when I get home.
4) I have not tried this with an A4 car. Obviously, the gear ratios will be off, but even if these are changed, I'm not sure how it will work as the whole torque converter really screws things up.
I'll try a third gear pull with the converter locked and post the results. I think it should still work, 3rd is 1:1.
It will be a day or two before I can try it, I'll have to wait for Tropical Storm Ida to leave town.
__________________
2004 Phantom Black A4 GTO
Mods-Flowmaster catback, Dynatech LT's, Vinci 099 cam 232*/240* .551"/.551" 117 lsa, Comp Pro Magnum Rockers, Edelbrock Victor Jr. Intake, Edelbrock 90mm TB, Patriot ported 243's, Procharger P1SC @ 8psi, Snow Meth Injection, Performabuilt Level 2 4L60E, Performabuilt 3K stall, 2-Bar SD tuned at home with HP Tuners.
[quote=Black04A4;6181088]I'll try a third gear pull with the converter locked and post the results. I think it should still work, 3rd is 1:1.
[quote]
with a 3rd gear pull, changing the appropriate cell values, and a locked verter it should work fine....
that said, when i tested it with my A4 unlocked(3000 stall), things got all kinds of wonky... i never got to make any locked runs as i discovered a critical lean condition when making the logs.... so the GTO is garaged until i get a chance to check things over..
but locking the verter in theory should fix the mess i found with the unlocked verter logs...
I've tried logging the trans output speed PID (PID.4111), and get zero...nada...nothing. I have an 04, does it not use that PID? Or is it my V2.23 of HPT?
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2004 Torrid Red M6. LS6 heads, TR224 cam, New Era/hardcore intake, Pacesetter V2 LT's with catless mids, Bassani/Sweet Thunder exhaust, LS-7 clutch, GMM Street Ripshift, Jantzer Performance Throttle Body, TB Bypass.
I've tried logging the trans output speed PID (PID.4111), and get zero...nada...nothing. I have an 04, does it not use that PID? Or is it my V2.23 of HPT?
Hmmm, GoatKart has logged Trans Output RPM (I believe) and he has an 04, so I don't think thats the issue. PID .4111 is the same PID in my version and I just realized that I have version 2.22 so I don't really know what to tell you.
yup logged it just fine... even double checked pid etc... still pid.4111
stickers: make sure your logging it in the table, and not just the chart... (not sure how familiar you are with hpt)
yeah, what he said. the table is where all the logged parameters are loaded. i think a nice feature for HPT would be if in the other places (chart, histogram, etc) the list of PIDs would be limited to just what you have loaded in the table and thus be available to avoid confusion.
2006 GTO Owner
She's VERY lean down there, so don't look for me to be doing this again. Hell, I didn't even know if I had it in me to lug her that bad.
lol
they
