comparing performance by videoing your speedo... Accurate??

[karatemaserati]

so I had a couple of performance mods done on my db9 and could instantly feel the increase in shove which was pretty dramatic but wanted to to compare how my car now went compared to other v12 derivatives... I know i could of dyno'd before and after but all you get from that is numbers which don't mean much in the real world, they can be wildly inaccurate and either make you cry or tell you that you have more power than a veyron.. depending on the dyno, the weather, the software ect.

I found a couple of separate video reviews of mk2 vanquish with acceleration runs where the camera is pointed at the speedo. I then downloaded the vids to an editor so I could scroll though the time (accurate to hundredths of a second) it took the needle to go between 40-100mph. The results I got were EXACTLY the same to the hundredth... Freak coincidence or a really accurate metric?

I know you are at the mercy of relying that the driver in the video is driving on flat, not in a head wind and doesn't weigh 50 stone, but its probably safe to say they have considered this.

im intending to do a run with filming my speedo and compare.. have found 2014 db9 and DBS speedo videos.. although the dbs video has quite a large parallax error

on paper the mods done should put me in DBS/ 2014 db9 territory

 

[allandwf]

There are phone apps that log it, as the Speedo may not be as accurate at certain points, plus you don't need to bother about setting up video, unless you want to go that route.

 

[Cyclone1]

Or buy / borrow a Dragy device as it’s very simple to use

 

[karatemaserati]

A draggy doesnt give me the data from the other cars though? the only data I have for the other cars is their analogue speedo readings... surely it would be best to compare like for like?

 

[allandwf]

A draggy doesnt give me the data from the other cars though? the only data I have for the other cars is their analogue speedo readings... surely it would be best to compare like for like?

Yes for visual purposes, but they could all be calibrated slightly differently , so it isn't really like for like, unless they use a common standard.

 

[davy83]

use a phone app and use the same app in different cars, preferably same phone too.

 

[Cyclone1]

A draggy doesnt give me the data from the other cars though? the only data I have for the other cars is their analogue speedo readings... surely it would be best to compare like for like?

Ok but have you checked the Dragy data for other cars? It covers many marques and models, plus the owners can declare the mods, so you can compare somewhat comparably

 

[Zep]

What you are proposing would rely on similar calibration. If you wanted it to be accurate to tenths, things like gradient, temperature, traction coefficient, altitude. tyre wear and temperature will influence the result, to name but a few.

But if it’s just for ***** and giggles it won’t matter at all.

 

[karatemaserati]

So I got a draggy...

not bad considering a vaquish2 does it in 8.85s on the autotopNL leaderboard