Dyno Maths Library

[FWombat]

Humm,  these seems to work for me, but for some reason after around 4k rpms theres a big drop off and then around 5500 rpms it comes back to where it was at 4k rpms.    

Often times a big, sudden rise or fall in the power graph is due going up or down a hill while making the log...

A power spike can also be caused by a slipping clutch...

- Brian

[93accordNOS]

It's not a sudden rise or fall,its like just a gradual dip from around 150 to 110 back to 150.  It's definately not from unlevel ground (I did this on the GSP) and I see it on 3 different pulls.  My clutch definately isn't slipping either.  Any other ideas what it might be from?  When I get home tonight I'll try and post it up for you too see if you would like.

[93accordNOS]

Ok, I played with it some more.  Well actually I just put in the numbers same as last time and it worked better this time.  The dip is gone.  Heres my results off of a couple different pulls.  My question is, why is there such a sudden drop off after 6000rpm?  Motor spins 7k easily and pulls the whole way.  BTW the top two are with the engine speed reading at normal, the bottom two are with it at fastest.  BTW don't ask what that "dead spot" in the top two is, I have no idea, probably just my crappy laptop not wanting to log.

[FWombat]

Ok, I played with it some more.  Well actually I just put in the numbers same as last time and it worked better this time.  The dip is gone.  Heres my results off of a couple different pulls.  My question is, why is there such a sudden drop off after 6000rpm?  Motor spins 7k easily and pulls the whole way.  BTW the top two are with the engine speed reading at normal, the bottom two are with it at fastest.  BTW don't ask what that "dead spot" in the top two is, I have no idea, probably just my crappy laptop not wanting to log.

If you're going to use the dyno maths library, you really need to use the internal logger.  The PC logger just isn't fast enough to get a really good sample rate.  Make sure that Engine speed is setup to log on one of the fast channels, and setup the internal logger at the fastest possible sample rate.  That will make sure you have good, clean data.

Then, once you've got logs from the internal logger, send email one to me, along with a copy of the math library you're using, and I'll tailor the filtering to your sample rate.  On the pictures you posted above, the reason the power graph comes up so late and drops off so soon is that it's overfiltered.  The filters in the library setup for the internal logger (250 samples/sec), but you're running on laptop logs (50 samples/sec, max).  Start using that internal logger!  

- Brian

[93accordNOS]

Ok did it with internal logging.  It looks to give more appropriate numbers, but has a lot of fluctuation.  Here's a link to download it.
http://home.comcast.net/~craibit/Abstract_from_internallog.stf

[FWombat]

Ok did it with internal logging.  It looks to give more appropriate numbers, but has a lot of fluctuation.  Here's a link to download it.
http://home.comcast.net/~craibit/Abstract_from_internallog.stf

The fluctuation you see in the power curves is due to your Engine Speed (RPM) signal being noisy.  If you look very closely at Engine Speed in the areas where the power curves fluctuate, you'll see that it kind of "bounces" around...it'll go from 3000 to 3010, then back down to 3006, and up to 3012...etc.

In any case, try this library.  I turned the filtering up to smooth out the curves.  It's not perfectly smooth, but if it was perfectly smooth than any REAL peaks or dips would be masked as well, and the whole point of the library would go down the drain.    

You'll still need to fill in appropriate weight, gear ratio, wheel sizes, etc...

- Brian


Edit:  I guess we can't attach files to posts any more.    PM me your email address, and I'll email you the new library with increased filtering.

[v8huntr]

i'm getting -130rwhp.  is there preset program for supra?  also how can i change car specs.

[FWombat]

i'm getting -130rwhp.  is there preset program for supra?  also how can i change car specs.

Go back and read.  There's no preset library for anyone (except 2nd gen VR-4s and Stealths, who can use the one I posted.)

- Brian

[CHEETAH]

brian, need some help, I dont have too many internal logs, i use a lot of laptop logs and i saw your recommendation to use internal for more sample rates. I get weird numbers if I try to apply your fwombat amtch calc to my log. I do not have VSS in my logs, can this still work ? what all is needed ? where can I email you my log sample where you can cater to give me hp/tw output if i give you slick size ? It doesnt not need ot be accurant, just consistent in terms of comparing each pass i make to see if the car accelerated better from more HP/TQ, etc.

feel free to PM me or email me gbrtuning@aol.com

thanks
Greg

[calvin_baank]

can't wait to buy my aem for my fully  built b16

[silver2k1cobra]

ok.  so there is filtering in RPS and Filtered _HP.  My question is I see different numbers in each.  on a graph what filter changes what?

I need more internal logs to work with this function and so far love what I see.  Just trying to get into the details to adjust the filtereing as needed and see if I can get usefull data from the laptop log even though it is slower.  since the only way to download the internal log is to have the car off.. nice to be able to see on the fly if changes are helping or hurting.

THanks again for all the time you have put into this.

[FWombat]

ok.  so there is filtering in RPS and Filtered _HP.  My question is I see different numbers in each.  on a graph what filter changes what?

I need more internal logs to work with this function and so far love what I see.  Just trying to get into the details to adjust the filtereing as needed and see if I can get usefull data from the laptop log even though it is slower.  since the only way to download the internal log is to have the car off.. nice to be able to see on the fly if changes are helping or hurting.

THanks again for all the time you have put into this.

There are three places filtering is employed:
     RPS - (FILTER X Engine Speed) /60
     DeltaRPS -  (DIFFERENTIATE Y RPS)
     Filtered_HP - (FILTER Z Raw_HP)

In the default library,
     X = 50
     Y = 25
     Z = 125

I've found that these values give me good results with my internal logging of Engine Speed at the highest rate.  If you want to play around with them, feel free.  I'd recommend reducing Z first, then X , and Y as a last resort.  All three have the same effect - smoothing out the graph - they're just applied at different points in the calculation cycle.  

In general, you should be getting a graph that LOOKS like a dyno sheet.  If your graph looks smoother than a dyno sheet, you need to turn down the filtering.  In extreme cases of over-filtering (like when you apply the library to a PC-log), you'll get a graph that looks like an extremely smooth mountain.   If you're getting lots of sudden peaks and valleys in the middle of the graph, then you need more filtering.

- Brian

[silver2k1cobra]

Thanks, Such a easy tool.. I’m hoping that with logging to the PC with the fastest rate I can at least get estimated info back.  that way I can get real-time feed back to changes to the tune.  Hate having to turn the car off to get the internal log file.  But understand how that is the only way to get accurate data back.

[93turbosi]

lol i have -45 hp and - 35.51 tq at 6700 rpms and 15 psi of boost on a built sohc vtec.  awesome no wonder it feels so fast

[DSMotorsport]

Just downloaded and used the math against my street pulls for 3rd gear and my datalogs from my last dragstrip pass.

seems to work perfectly for me with an Evo8.  got the gear ratio info off the web, I knew the weight from scale at the track.

Showing 297awhp and about 285-290wtq (can't see peak torque on the drag passes, as rpm doesn't get that low).

that seems pretty close to what I would be expecting on a dynojet for a 3400total weight car going 108 in the 1/4.

Im impressed...
Thanks to the maker.