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Author Topic: Comparing DL-1 Files btwn two cars | how accurate is the mapping?
Vick Verified Driver
Do they sell spec training wheels?

Region: NYR
Car #: 12
Year : 1991
Posts: 620
Status: Offline
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Random question but wondering if anyone has the answer.

A fast driver up here was nice enough to share some of his data with me. I've overlayed two of our best laps, and other than the obvious fact that he's faster than me EVERYWHERE (except for the one corner I'm supposed to throw away....), I'm looking at our lines and wondering if I can compare them or whether it's just a garbage in, garbage out analysis.

Thoughts? Are our little red line and black lines actually in relation to where our cars were on the track or is there just too much noise there to analyze it between two seperate units in two different cars.

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http://www.volko.com

Dan Tiley Verified Driver Series Champ
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Region: SEDIV
Car #: 33
Year : Whatever's Available!
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I've had good luck overlaying my own runs from the same track even when the data has been taken months or years apart. I'd feel pretty comfortable overlaying my data with another driver's to compare basic race lines as well. One thing I noticed, however is that you'll sometimes see a global shift of a few feet (or more) of the entire dataset from one visit or from one vehicle to another.

The DL1 software allows you shift an entire data set in X & Y so that your overlays will be spot on. It's under "Run Manager" on the "General" tab. Use the toggles under "Manual Map Offset" to move each run set where you want them.

Just pick a few spots on the track where you know that you're consistently running the same line (ie. on the outside edge of certain straights before turn-in). Use a few of those points to align the different datasets.

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Dan Tiley

Sponsored by Race Engineering

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Kyle Burkhardt
Member

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I use Traqmate so I'm not familiar with the capabilities of your system, but I bet that the actual line taken makes less of a difference than does the acceleration and deceleration graphs over distance. You'll easily see where he's braking later, braking less, carrying more speed and accelerating earlier. That's where the time is. At this level, we all can figure out the line.

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Kyle Burkhardt
NASA Midwest
#12 SM

AllardK3 Verified Driver Made Donation to Website Series Champ
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Region: Az
Car #: 13
Year : 1993
Posts: 59
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Vick,

I use the overlay function all the time to compare with my team mate. On our 2 systems, the results are extremely consistent. The only strange thing, is my system has some kind of a bug in it that makes it look like I don't brake as late as my team mate on some of the high speed corners.....

The G and speed overlays are also really useful.

Mike

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Mike Donick

Nigel Stu Verified Driver
Member

Region: Detroit
Car #: 66
Year : 1992
Posts: 105
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Both Dan and Kyle have made some excellent comments and gives you a good place to start.

The accuracy of the systems will not allow you to see if your turn-in, apex and track-out points are within 3 inches of the other guys. But if you move the lines so they match up like Dan said, you CAN see any gross differences in lines taken (significantly different lines) and the relativedifference in lines through a corner (such as if the other guy is tracking out further than you - are you using all the track?). So its useful, but not the full story.

To help with lining up the runs, turn on the map background so you can overlay the lap traces onto the track map. (This is in under the 'options' button in the track map box - check the 'Download map as background')


And then what Kyle said - once you get the data matched up fairly well, switch over to the 'time slip' and 'g analysis' tabs. Once you see where the big gaps are, you can look at the detail for your data vs. his data to see what is being done differently.


Good luck!

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Ben Schaut
Schaut Speed Motorsports
GLDiv / WHRRI
#66 Blue/White/Black

Dan Tiley Verified Driver Series Champ
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Region: SEDIV
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quote:
Originally posted by AllardK3:
The only strange thing, is my system has some kind of a bug in it that makes it look like I don't brake as late as my team mate on some of the high speed corners.....

I bet that correlates really well with those lap time errors you've been getting too, right?

--------------------
Dan Tiley

Sponsored by Race Engineering

Spec Miata's fastest and best supported engine program!

Vick Verified Driver
Do they sell spec training wheels?

Region: NYR
Car #: 12
Year : 1991
Posts: 620
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Thanks guys. This was a big help.

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http://www.volko.com

Kyle Burkhardt
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quote:
Originally posted by AllardK3:
The only strange thing, is my system has some kind of a bug in it that makes it look like I don't brake as late as my team mate on some of the high speed corners.....

Suuuuurrrre! My engineer tells me "the data never lies" when I tell him I'm braking late or not lifting. [Big Grin]

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Kyle Burkhardt
NASA Midwest
#12 SM

AllardK3 Verified Driver Made Donation to Website Series Champ
Member

Region: Az
Car #: 13
Year : 1993
Posts: 59
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Dan,

The surprising thing is since I got my Race Engineering motor the laptimes are no longer an issue.....

I also had a similar glitch with a video system once in a borrowed Fiero.........It made it look like I was drifting the hell out of a borrowed car. Really strange....

Mike

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Mike Donick

Dan Tiley Verified Driver Series Champ
Are you followin' me, camera guy???

Region: SEDIV
Car #: 33
Year : Whatever's Available!
Posts: 311
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quote:
Originally posted by AllardK3:

I also had a similar glitch with a video system once in a borrowed Fiero.........It made it look like I was drifting the hell out of a borrowed car. Really strange....

You ain't kiddin....

http://www.youtube.com/watch?v=HTxaTbJDFGc

--------------------
Dan Tiley

Sponsored by Race Engineering

Spec Miata's fastest and best supported engine program!

AllardK3 Verified Driver Made Donation to Website Series Champ
Member

Region: Az
Car #: 13
Year : 1993
Posts: 59
Status: Offline
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Good times, Man it's tough to believe that was 6 or seven years ago!

That was a fun little Fiero that you put together.

Mike

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Mike Donick

   

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