Dyno Maths Library

[Scott Warwick]

OK, I can't seem to get this thing to work properly. My hp numbers are way off, sometimes into the negatives...........any help would be appreciated. I can send you a log, my math and all my info if necessary. 

[0vrBsT]

OK, I can't seem to get this thing to work properly. My hp numbers are way off, sometimes into the negatives...........any help would be appreciated. I can send you a log, my math and all my info if necessary. 

Did you import the Library?  Do this:

1) Open up the Log file in AEMLog.
2) Maths -> Open Library
3) Select the FWombat_Dyno_Library.mth
4) The List of equations will come up.  Enter the necessary values as I mentioned in the previous post.
5) Click Close
6) Maths -> Recalculate
7) Select All, then click OK
You'll see a little progress bar calculating the equations.
9) Right click on your log graph and Select Overlays, and select _Wheel_HP and_Wheel_Torque.


Note on editing the equations:  The Equation editor is... well... buggy.  There's no other way to say it.  When editing the constants to put in the values for your car, DO NOT USE THE BACKSPACE KEY!!!  I found that this often triggers incorrect edits.  Also, do not click the cursor to the middle of the equation.  Click at the beginning to put the cursor there, and then use ONLY the left and right keys to move the cursor.  Use the ONLY the delete key to delete. 

Even with these tips, sometimes equations get mangled by the editor.  When you close the equation, look at it on the list to make sure it's still what you're expecting.  If it's not, edit it again.

- Brian

if you follow this to a tee everything will work fine.Its just finding out the right settings for your vehicle setup.i had the same problems you are having untill i read this thread three times.

[Scott Warwick]

I still don't  know what I'm doing wrong. I entered everything just as stated and my hp and tq go down as rpms go up for soome reason. Why would it be backwards?

[Scott Warwick]

this is what I'm working with, anyone want to take a look? 

[FWombat]

this is what I'm working with, anyone want to take a look? 

1) You're not doing full throttle pulls from low RPM to redline.   
The Dyno Library can only figure out your HP/TQ accurately when you give it a log of a full throttle pull across the RPM band.  Your log has a bunch of small pulls of less than a few thousand RPMs, half of them with throttle movement in the middle.   Do a rolling start from low RPM (2000, perhaps), and keep the throttle wide open until redline. 

2) You're not logging at the fastest internal rate. 
I had to cut the filtering on the library by like a factor of 10 in order to get the library to put out numbers that made sense.  Lower sampling rates = less accurate results.  If the sampling is way too low, the numbers will be non-sensical.  Your log was at a fairly slow sampling rate.  I've recently been using the second-fastest rate (125 samples/sec) as it gives accurate results but downloads faster.

Go get a log of a long smooth pull to redline, on flat ground, at the second-fastest internal sampling rate.  Then try the library and let us know how it looks.  I'll be happy to adjust the library if things are still wonky.

- Brian

[FWombat]

Seems to be working for me but my plot drops off WAY before I end the pull like many others have experienced. I'm only using 1 sample rate slower than 250 with the internal logs. Any idea how I should adjust the sampling rate to yield better results with the lower sampling rate?

Post your log and math library, and I'll take a look.

- Brian

[mikeymustang]

Will this work on a 1/4 run?.....if so let me know ill post my log of a 9.66 @141 run

thanks

Mike

[0vrBsT]

fwombat can you explain how to figure out the cd_drag and cd_area on my 95 civic hatch.I am useing CD_DRAG = .34 and CD_AREA = 20 , These seem to be working fine but i wanted to make sure i have the right settings for my car.any help would be appreciated*.

Thanks,Danny

[FWombat]

Will this work on a 1/4 run?.....if so let me know ill post my log of a 9.66 @141 run

thanks

Mike

No, it wouldn't work well on the quarter mile pull.  It'll only work for one gear at a time, and any wheel spin would make the HP numbers go through the roof. 

It works on the same logic as a dyno, so you need to give it the same data as a dyno.  A smooth, straight pull in one gear.

[FWombat]

fwombat can you explain how to figure out the cd_drag and cd_area on my 95 civic hatch.I am useing CD_DRAG = .34 and CD_AREA = 20 , These seem to be working fine but i wanted to make sure i have the right settings for my car.any help would be appreciated*.

Thanks,Danny

Google it.  That's how I got mine.

[0vrBsT]

fwombat can you explain how to figure out the cd_drag and cd_area on my 95 civic hatch.I am useing CD_DRAG = .34 and CD_AREA = 20 , These seem to be working fine but i wanted to make sure i have the right settings for my car.any help would be appreciated*.

Thanks,Danny

Google it.  That's how I got mine.

thanks for the tip.For anyone looking for the right cd_drag and cd_area numbers for your car go herehttp://www.mayfco.com/analyses.htmthere is a list of all makes and models of vehicles.Also there is alot of usefull info on here.

[Vobra46]

Will having an automatic with a stall mess things up? I have been trying to use this thing and its reading WAY high especially the trq values.

TIA,
Bob

[FWombat]

Will having an automatic with a stall mess things up?

It could.  The library uses RPM and your gear information to calculate the vehicle's velocity.  Any time engine speed is not directly linked to vehicle speed -- clutch slip, tire spin, automatic tranny stall, etc -- the library's readings will be off.

It should still work though, as long as the tranny is putting all the engine's power to the wheels, and the wheels have full traction. 

[BoostedVR4]

I haven't tried this since last year with my car.  I just gave it a shot using a long 3rd gear log I made leaving the dyno this week.  This time I actually looked up my drag, and area for the car.  Guessing the weight of my passenger, your maths read about 13 more HP than the dyno did.  (dynojet at MSP)  The added HP could easily be the colder temps outside + actual airflow around the IC.  (also the guessed weight)

All in all, this is a perfect tool to give a rough estimate of power gain/loss. 

[Evo-L]

I still don't  know what I'm doing wrong. I entered everything just as stated and my hp and tq go down as rpms go up for soome reason. Why would it be backwards?

This is also my problem, FWombat, do you know what could be up?