DDQ

I was using the Butt Dyno 6 spreadsheet. One question: Where do the "time stamp decel" numbers come from?

Thanks!

here is the butt dyno thread:<ul><li><a href="https://forums.audiworld.com/vag/msgs/457.phtml">https://forums.audiworld.com/vag/msgs/457.phtml</a</li></ul>

GA4 S-line

I would have a guess thats is the time on the deceleration part that the corisponding speed was met...
i.e. after 2 seconds he reached 2080 RPM and 41km/h, he rached the same speed after 100secs..after putting down the clutch after redlining...according to the instruction theres a growth function in excel to help match the acc and decl. speeds. either that or will have to try and do it manually.

Dont know about in the US but here in the UK its going to be hard to find a straight quite road to do this....

Andy@Ross-Tech

The first thing I do with raw data is make a quick graph of speed-vs-time. This shows what the accel and decel curves look like. I used a Scatter (X-Y) chart type and used:

X-values: $B$8:$B$311
Y-values: $E$8:$E$311

Then, I highlighted the accel data in red, and the decel data in blue.

I made another graph of time-vs-speed for just the decel portion of the data. I used a Scatter (X-Y) chart type and used:

X-values: $E$51:$E$311
Y-values: $B$51:$B$311

Then, I selected that data and chose "Add Trendline". You may need to play with different trendline types to get something that fits your curve well. I found that a 3rd order polynomial fit great.

I selected the trendline and chose "Format Trendline". Under "Options" I checked the choice for "Display Equation on Chart".

Now that the equation was on the chart, I selected it and used the "Increase Decimal" command in the Excel toolbar to give the equation more decimal places. Just crank it way up there, maybe 12-15 places showing should be fine.

y = -0.00001966013549x3 + 0.01010649042580x2 - 2.11664390630149x + 171.35689830770700

Now I copied that formula and pasted it into cell G8 with the heading "Decel calculated". Now, it doesn't yet work as a formula until we replace the "x" with the cell that contains the X-value, E8 in this case. Remember to replace 9x3 with 9*E8^3 for example. So, in cell G8, I have the formula:

-0.00001966013549*E8^3 + 0.0101064904258*E8^2 - 2.11664390630149*E8 + 171.356898307707

Now that we have decel stamps that correspond to each accel speed, they can be pasted into the Butt Dyno.<ul><li><a href="http://www.ross-tech.net/andy/vwfiles/butt-dyno/crunched-data-01.xls">http://www.ross-tech.net/andy/vwfiles/butt-dyno/crunched-data-01.xls</a</li></ul>

DDQ

Thanks for the great info. I'll try this later on.