Shiftpoints Analysis
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Shiftpoints Analysis
<center><img src="http://www.ross-tech.com/vag-com/cars/Examples/shiftpoints2.gif"></center><p>Here's the general idea - acceleration in a single gear corresponds closesly with the torque curve. Your acceleration (change in speed over change in time) is greatest at the torque peak, and tapers off after the torque peak.
Using VAG-COM, I logged a full throttle run in each gear on a straight, flat road. I used block 005. Change in speed over change in time is acceleration. 9.81 m/s^2 = 1 g. The optimal shiftpoints are where the curves cross.
So, for my specific setup (note, this varies by car, mods, etc.), the optimal acceleration is obtained by shifting at:
1>2 6700 rpm (34 mph)
2>3 6800 rpm (62 mph)
3>4 6200 rpm (86 mph)
In Excel, I created 6th order polynomial trendlines for each data series (sounds WAY more complicated than it really is). This basically smooths out the data to make it more readable.
Interesting note: You will always get your fastest acceleration by shifting AFTER the horsepower peak (unless you have a CVT, in which case you will have the fastest acceleration by keeping the engine AT the horsepower peak).<ul><li><a href="http://www.ross-tech.com/vag-com/cars/Examples/shiftpoints.xls">Shiftpoint Spreadsheet</a></li></ul>
Using VAG-COM, I logged a full throttle run in each gear on a straight, flat road. I used block 005. Change in speed over change in time is acceleration. 9.81 m/s^2 = 1 g. The optimal shiftpoints are where the curves cross.
So, for my specific setup (note, this varies by car, mods, etc.), the optimal acceleration is obtained by shifting at:
1>2 6700 rpm (34 mph)
2>3 6800 rpm (62 mph)
3>4 6200 rpm (86 mph)
In Excel, I created 6th order polynomial trendlines for each data series (sounds WAY more complicated than it really is). This basically smooths out the data to make it more readable.
Interesting note: You will always get your fastest acceleration by shifting AFTER the horsepower peak (unless you have a CVT, in which case you will have the fastest acceleration by keeping the engine AT the horsepower peak).<ul><li><a href="http://www.ross-tech.com/vag-com/cars/Examples/shiftpoints.xls">Shiftpoint Spreadsheet</a></li></ul>
AudiWorld Expert
Joined: Mar 2000
Posts: 29,189
Likes: 5
From: Raleigh, NC
Yeah, I've done the same, yet I keep Accleration in MPH/s...instead of g....
It's nice to see your acceleration in "MPH per second", as more people can understand that significance... ie when you are accleration at greater than 10MPH per second.
Also, did the 6th order smooth it out too much? Did you compare where they crossed at say, 2nd order?
Also, did the 6th order smooth it out too much? Did you compare where they crossed at say, 2nd order?
AudiWorld Expert
Joined: Mar 2000
Posts: 29,189
Likes: 5
From: Raleigh, NC
And here it is...
I was just interested in "highway" shifting at the time, so I had just logged 3rd-5th. This shows:
3rd -> 4th shift at 93mph/6500rpms (where yellow crosses pink)
4th -> 5th shift at 113mph/6200rpms (where pink crosses blue)
<img src="http://pictureposter.audiworld.com/139/accel.jpg">
3rd -> 4th shift at 93mph/6500rpms (where yellow crosses pink)
4th -> 5th shift at 113mph/6200rpms (where pink crosses blue)
<img src="http://pictureposter.audiworld.com/139/accel.jpg">
AudiWorld Expert
Joined: Mar 2000
Posts: 29,189
Likes: 5
From: Raleigh, NC
Just out of curiosity, I plotted with Acceleration in g's to compare....
<img src="http://www.ross-tech.com/vag-com/cars/Examples/shiftpoints2.gif">
<img src="http://pictureposter.audiworld.com/139/accel3.jpg">
<img src="http://pictureposter.audiworld.com/139/accel3.jpg">
New Member
Joined: May 2007
Posts: 1
Likes: 0
Re: Shiftpoints Analysis
i just did this on my 01 jetta 1.8t.
because of warranty issues at the end of last summer, then needed some cash so i sold my exhaust sitting my my garage (eek) and took off my TIP, so i'm currently stock, but have the apr 93 chip.
i found my best shift points are almost the exact same:
1st>2nd 6900 (37mph)
2nd>3rd 7000 (64mph)
3rd>4th 6100 (84mph)
when i had my 3" DP w/ dump tube i ran a 13.7@103mph and was shifting at 7k for 1st>2nd and 2nd>3rd and 6800 for 3rd>4th (friends recomendation), also had my friend's drag slicks on. also dyno'd 213whp/247wtq.
this was very helpfull. going to do the <a href="https://forums.audiworld.com/vag/msgs/457.phtml">butt dyno</a> test after i get my parts back in to compare it to the dynojet. and hope for a slightly faster 1/4 mile with my 3rd>4th shift a bit earlier.
because of warranty issues at the end of last summer, then needed some cash so i sold my exhaust sitting my my garage (eek) and took off my TIP, so i'm currently stock, but have the apr 93 chip.
i found my best shift points are almost the exact same:
1st>2nd 6900 (37mph)
2nd>3rd 7000 (64mph)
3rd>4th 6100 (84mph)
when i had my 3" DP w/ dump tube i ran a 13.7@103mph and was shifting at 7k for 1st>2nd and 2nd>3rd and 6800 for 3rd>4th (friends recomendation), also had my friend's drag slicks on. also dyno'd 213whp/247wtq.
this was very helpfull. going to do the <a href="https://forums.audiworld.com/vag/msgs/457.phtml">butt dyno</a> test after i get my parts back in to compare it to the dynojet. and hope for a slightly faster 1/4 mile with my 3rd>4th shift a bit earlier.
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