Calling Cruzad3r & Schwing. Here is my first shot at the "Butt Dyno" results........
03-13-2008, 01:19 PM
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Calling Cruzad3r & Schwing. Here is my first shot at the "Butt Dyno" results........
First - some history:
A couple of weeks ago Cruzad3r posted some HP & TQ numbers obtained from Block 120 of the Vag-Com and asked me to do likewise for comparison. Steve again warned me that those numbers are not at all realistic if the car has been significantly modded, as mine is. Steve suggested that I plot out Blocks 002 (air mass), 118 (Temps & N75 duty cycle), & 204 (boost pressure) instead.
I did so and sent them to Steve and he said everything looked good but to slightly adjust the onset and regulator of my BM, which I did.
Steve also suggested that Andy's (from Ross-Tech) "Butt Dyno" spreadsheet is a good indicator of the actual wheel HP & Torque of the car instead of wasting my time even trying Block 120.
Second - some Info on the "Butt Dyno" calculations:
I looked up Andy's "Butt Dyno" Excel Spreadsheet and was pleasantly surprised at the accuracy of the details, specially the ingenuity of the deceleration part to account for air-drag and friction losses. As stated in the accompanying link: "This is the same type of calculation that is done with a DynoJet, except you are using your vehicle's mass instead of the mass of the rollers. It can be argued that this type of measurement is even more accurate than a DynoJet since you are getting real-world airflow unlike the fans used by dyno shops. So, in answer to your question, Group 120 should give you a picture of how the engine perceives torque generation. This can be skewed by some mods and chips. The "Butt Dyno" should give you a picture of how power is being used to accelerate the vehicle. This is a more useful, real world measurement of wheel power, but is considerably more complicated to use." And having used it I believe it.
Third - some results using a third gear run:
This is my first shot at using the "Butt Dyno" and I changed the logic somewhat. Andy uses the raw Velocity data, which does not have enough detail (Vag-Com produces a whole number without any decimal places) to provide a smooth transition from one time stamp to the next. This produces a lot of wiggles in the results and Andy uses a "smoothing" (three point averaging) technique to attempt to produce a steadier curve. The results are still quite jumpy for my taste. I chose to curve fit the raw velocity data to produce a smooth curve before employing the calculations. The result is much smoother HP & TQ curves which need no further manipulation.
The Polynomial velocity curve fit is presented in the chart below. Also presented is the data file with both the raw and the fitted velocities shown side-by-side for comparison.
And finally the wheel HP & TQ curves are presented for my first run which was in third gear using only one Block (005) to collect the data which speeds up the process to about 3-data-points/second. The first time I logged three blocks (002, 120, & 005) and this slowed down the data gathering to about 1/second (not enough data generated during the acceleration run.
Fourth - I also ran a 2nd gear excursion which I haven't looked at yet but which I will analyze as we speak to see the differences from the enclosed 3rd gear test. I will keep you appraised of the situation.
This is the chart of the Raw & the Polynomial Fitted Velocities:
<img src="http://pictureposter.audiworld.com/105167/bc_polynomial_fit_to_velocity_0.3s_data_031208.jpg ">
This is the data file showing both the raw & the fitted velocities side-by-side. The decel data (green) is obtained from another spreadsheet denoted in the "additional instructions" thread at the bottom of the link.
<img src="http://pictureposter.audiworld.com/105167/bc_raw__fitted__0.3s_data_3rd_gear_031208.jpg">
Finally this is the Wheel HP & TQ for my vehicle as if measured by a dynamometer but it's really the "Butt Dyno" Calculations.
<img src="http://pictureposter.audiworld.com/105167/bc_butt_dyno_3rd_gear_0.3s_data_031208.jpg">
BC<ul><li><a href="http://forums.audi
A couple of weeks ago Cruzad3r posted some HP & TQ numbers obtained from Block 120 of the Vag-Com and asked me to do likewise for comparison. Steve again warned me that those numbers are not at all realistic if the car has been significantly modded, as mine is. Steve suggested that I plot out Blocks 002 (air mass), 118 (Temps & N75 duty cycle), & 204 (boost pressure) instead.
I did so and sent them to Steve and he said everything looked good but to slightly adjust the onset and regulator of my BM, which I did.
Steve also suggested that Andy's (from Ross-Tech) "Butt Dyno" spreadsheet is a good indicator of the actual wheel HP & Torque of the car instead of wasting my time even trying Block 120.
Second - some Info on the "Butt Dyno" calculations:
I looked up Andy's "Butt Dyno" Excel Spreadsheet and was pleasantly surprised at the accuracy of the details, specially the ingenuity of the deceleration part to account for air-drag and friction losses. As stated in the accompanying link: "This is the same type of calculation that is done with a DynoJet, except you are using your vehicle's mass instead of the mass of the rollers. It can be argued that this type of measurement is even more accurate than a DynoJet since you are getting real-world airflow unlike the fans used by dyno shops. So, in answer to your question, Group 120 should give you a picture of how the engine perceives torque generation. This can be skewed by some mods and chips. The "Butt Dyno" should give you a picture of how power is being used to accelerate the vehicle. This is a more useful, real world measurement of wheel power, but is considerably more complicated to use." And having used it I believe it.
Third - some results using a third gear run:
This is my first shot at using the "Butt Dyno" and I changed the logic somewhat. Andy uses the raw Velocity data, which does not have enough detail (Vag-Com produces a whole number without any decimal places) to provide a smooth transition from one time stamp to the next. This produces a lot of wiggles in the results and Andy uses a "smoothing" (three point averaging) technique to attempt to produce a steadier curve. The results are still quite jumpy for my taste. I chose to curve fit the raw velocity data to produce a smooth curve before employing the calculations. The result is much smoother HP & TQ curves which need no further manipulation.
The Polynomial velocity curve fit is presented in the chart below. Also presented is the data file with both the raw and the fitted velocities shown side-by-side for comparison.
And finally the wheel HP & TQ curves are presented for my first run which was in third gear using only one Block (005) to collect the data which speeds up the process to about 3-data-points/second. The first time I logged three blocks (002, 120, & 005) and this slowed down the data gathering to about 1/second (not enough data generated during the acceleration run.
Fourth - I also ran a 2nd gear excursion which I haven't looked at yet but which I will analyze as we speak to see the differences from the enclosed 3rd gear test. I will keep you appraised of the situation.
This is the chart of the Raw & the Polynomial Fitted Velocities:
<img src="http://pictureposter.audiworld.com/105167/bc_polynomial_fit_to_velocity_0.3s_data_031208.jpg ">
This is the data file showing both the raw & the fitted velocities side-by-side. The decel data (green) is obtained from another spreadsheet denoted in the "additional instructions" thread at the bottom of the link.
<img src="http://pictureposter.audiworld.com/105167/bc_raw__fitted__0.3s_data_3rd_gear_031208.jpg">
Finally this is the Wheel HP & TQ for my vehicle as if measured by a dynamometer but it's really the "Butt Dyno" Calculations.
<img src="http://pictureposter.audiworld.com/105167/bc_butt_dyno_3rd_gear_0.3s_data_031208.jpg">
BC<ul><li><a href="http://forums.audi
03-13-2008, 01:51 PM
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Since this is wheel HP and since the drivetrain losses are about.......
20% for our TTs. The Engine power should be about 272HP which is very plausible but I was hoping for more. I can't think of many more mods that I can do that would increase the HP much above this value, short of a BT.
BC
BC
03-13-2008, 02:52 PM
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the TQ is low... compare to other people who have dyno their car. i did multiple run in same gear
and different gear; meaning i do a run in 3th gear, loop around same road do another run. loop around change to 4th gear and then return. you do have to find a long stretch of road because the decelerating part is amazing long compare to the acclerating. wat did you put for your car weight?
03-13-2008, 03:14 PM
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The weight I'm using is 3442 lb. I've found a stretch of road that's......
flat as a pancake and straight as an arrow for over a mile. It's an access road running next to the Xpressway. No traffic on it to speak of. A perfect place for this sort of shenanigance.
When I used the limited data (1/sec) and Andy's smoothing routine I got the following graph which produced higher TQ with the same HP (the eight data points is all I had to work with):
<img src="http://pictureposter.audiworld.com/105167/1sec_data_3rd_gear_031108.jpg">
What kind of numbers did you get
BC
When I used the limited data (1/sec) and Andy's smoothing routine I got the following graph which produced higher TQ with the same HP (the eight data points is all I had to work with):
<img src="http://pictureposter.audiworld.com/105167/1sec_data_3rd_gear_031108.jpg">
What kind of numbers did you get
BC
03-13-2008, 03:32 PM
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i'll send it to you tomorow. it's on my work comp. i think my calculations are much different than
yours because my decelerating graph looks different. i do need an email addy or you can email me at ravern_@hotmail.com
my dyno day was canceled due to rain last sat so there isn't any real data to compare with. once i have that i can compare and determine which is the best guess method to calculate tq and hp through vagcom
my dyno day was canceled due to rain last sat so there isn't any real data to compare with. once i have that i can compare and determine which is the best guess method to calculate tq and hp through vagcom
03-13-2008, 04:06 PM
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Here are the splits between the accel & the decel portions of the HP....
<img src="http://pictureposter.audiworld.com/105167/hp_accel-decel_components.jpg">
