Ad: Move Over VBOX, Dragy is here!

[Terry@BMS]

The function is similar to a VBOX that we've all been using to accurately measure performance up till now. Like the VBOX you can set it up to average the last 60' over the 1/4 mile OR take absolute speed. You can set it to include a 1' rollout, or not include a 1' roll out.

They've set it up to closely match a track, for 1/4 mile. Including 12' roll out, and average over last 60' for trap.

Tracks can be up to 1 degree negative slope but most are less. Official NHRA tracks probably have to be perfectly level.

 

[Erichale77]

Official NHRA tracks probably have to be perfectly level

No they do not. Some dip mid track and slope upwards towards end.

 

[R.G.]

What's the advantage of using this rather than your average smart phone internal gps with an app that can measure those metrics?

 

[Terry@BMS]

What's the advantage of using this rather than your average smart phone internal gps with an app that can measure those metrics?

Phone GPS runs at 1-2hz. So while it's good enough for navigation, its no where near precise enough for performance monitoring. Nor do the other apps verify slope or produce a nice VBOX like plot. In addition this can overlay your performance over video (on IOS now, coming for Android soon) so at races when you're filming them you can also have it show 60-130mph, 100-200kmh, etc, right in the video. Really slick.

 

[Bmwfixerguy1]

What's the advantage of using this rather than your average smart phone internal gps with an app that can measure those metrics?

I think they are too slow. That's just an educated guess though.

Think of the way your phone gets all jumpy and skitchy with directions. Think that can produce down to the 100th accurate

 

[R.G.]

I think they are too slow. That's just an educated guess though.

Think of the way your phone gets all jumpy and skitchy with directions. Think that can produce down to the 100th accurate

Yea, can't get hz spec on iphone 8, V-box sport listed at 20hz maybe?

 

[JOEinSD]

I’ve never had anything like this, VBOX or other.. so I have a few questions:

1) Stupid question here- Where does the slope data come from? Assuming from the gps data?

2) Still need to play around with mine, but when a run is “invalid” due to “data loss”, what could that be?

3) My phone is typically mounted in landscape in the car. Are there any plans for the app to work in landscape?

 

[aus335iguy]

I just use dash command... connects to OBD for speed so gps isn’t needed. If your speedometer is accurate you’re good to go. Cheaper, won’t calculate rollout but accurate enough to measure Performance increases

 

[langsbr]

I’ve never had anything like this, VBOX or other.. so I have a few questions:

1) Stupid question here- Where does the slope data come from? Assuming from the gps data?

2) Still need to play around with mine, but when a run is “invalid” due to “data loss”, what could that be?

3) My phone is typically mounted in landscape in the car. Are there any plans for the app to work in landscape?

Yes, GPS gives elevation data, and it can track the change in elevation over the run. I don't have a Dragy yet so I can't say what the data loss results from. Where do you have it mounted/set? I would think the closer you can get to a window so it could have best possible line of site would be the best.

I just use dash command... connects to OBD for speed so gps isn’t needed. If your speedometer is accurate you’re good to go. Cheaper, won’t calculate rollout but accurate enough to measure Performance increases

Accurate unless you have wheelspin, then the car thinks you are going faster when you really aren't.

 

[JOEinSD]

Yes, GPS gives elevation data, and it can track the change in elevation over the run. I don't have a Dragy yet so I can't say what the data loss results from. Where do you have it mounted/set? I would think the closer you can get to a window so it could have best possible line of site would be the best.

I threw it in the top left corner of my dash. It’s not a permanent location, was just testing. There are 2 dots on the app showing satellite lock; both were on. Like I mentioned, though, I still need to play with it a little more. Maybe it needs to learn or something for a little..

 

[Terry@BMS]

I just use dash command... connects to OBD for speed so gps isn’t needed. If your speedometer is accurate you’re good to go. Cheaper, won’t calculate rollout but accurate enough to measure Performance increases

The JB4 Mobile app can do that also, but CANbus road speed is not nearly accurate enough for these sorts of calculations. Useful for back of the napkin sorts of measurements but high speed GPS systems like dragy and vbox, provide highly accurate and repeatable results including slope that are equivalent to what you'd get at a real track. And in the case of these runway events with portable timing equipment, sometimes more accurate.

 

[Terry@BMS]

Yea, can't get hz spec on iphone 8, V-box sport listed at 20hz maybe?

JB4 Mobile also reads phone GPS. It's around 1hz on most phones max speed. Good for navigation but not accurate enough for this level of performance measurement.

 

[dyezak]

I just use dash command... connects to OBD for speed so gps isn’t needed. If your speedometer is accurate you’re good to go. Cheaper, won’t calculate rollout but accurate enough to measure Performance increases

Considering BMW purposefully skews the speedometer I don't think that you'll ever get accurate results with dash command. Even re-coding to remove the overestimation adjustment doesn't bring it back to reality completely...you have to perform custom adjustments to get it correct which is fairly advanced coding.

http://www.e90post.com/forums/showthread.php?t=688219

 

[Tony@VargasTurboTech]

Bought a dragy, and did some testing yesterday at the strip, and its exactly as I thought. While Dragy is a fun toy and is reasonably accurate, it could never be used instead of track timing equipment to claim actual 1/4 or 1/2 mile records.

Slip is shown, as are dragy results.

60 ft: Slip 1.670 - Dragy 1.73
330: Slip 4.811 - Dragy 4.84
660: Slip 7.358 - Dragy 7.38
1/4 Mile ET: Slip 11.282 - Dragy 11.31
1/4 trap: Slip 125.71MPH - Dragy 126.80

So the important stats, 60 ft, and 1/4 mile ET, and Trap. 60 is off by quite a bit, ET is decent, the trap is off by more than a full MPH. The dragy is fun and easy to use, but it's just that. No way it could be a substitute for real timing equipment.

Note: This was not an N54. This was our MK7 GTI, running at nowhere near full potential.

 

[Traf]

Close enough !

 

[Tony@VargasTurboTech]

Close enough !

For fun sure. For offical events, no its not... A full MPH trap is a huge difference

 

[Payam@BMS]

Bought a dragy, and did some testing yesterday at the strip, and its exactly as I thought. While Dragy is a fun toy and is reasonably accurate, it could never be used instead of track timing equipment to claim actual 1/4 or 1/2 mile records.

Slip is shown, as are dragy results.

60 ft: Slip 1.670 - Dragy 1.73
330: Slip 4.811 - Dragy 4.84
660: Slip 7.358 - Dragy 7.38
1/4 Mile ET: Slip 11.282 - Dragy 11.31
1/4 trap: Slip 125.71MPH - Dragy 126.80

So the important stats, 60 ft, and 1/4 mile ET, and Trap. 60 is off by quite a bit, ET is decent, the trap is off by more than a full MPH. The dragy is fun and easy to use, but it's just that. No way it could be a substitute for real timing equipment.

Note: This was not an N54. This was our MK7 GTI, running at nowhere near full potential.

View attachment 7917 View attachment 7918

Wish you took the Vbox too!

 

[dyezak]

It would be interesting to measure its consistency. If the precision is there for consistent measurement, even if it isn’t accurate it would be a great tuning aid.

 

[langsbr]

It would be interesting to measure its consistency. If the precision is there for consistent measurement, even if it isn’t accurate it would be a great tuning aid.

Exactly. How many passes were compared? Just one? It looks like all of the results are within 1% or less variance, which is really good for a $150 tool. I remember G-tech devices from back in the day that cost more that were off by 10mph.

It's fairly easy for me to go out on the highway to get a quick pull and see how well my car performs, as well as comparative differences with changes. Getting to the closest dragstrip is a timing and scheduling headache. I could live with a general idea of what my car does within 1mph and .05 seconds.

 

[Terry@BMS]

It would be interesting to measure its consistency. If the precision is there for consistent measurement, even if it isn’t accurate it would be a great tuning aid.

We had them in our cars the last SS and NFZ events and they always matched up closely with the VBOX. The VBOX screen itself is not smart enough to do 1' rollout for time to distance and not for time to speed, or to average last 60' of speed on 1/4 mile traps, so you need to use the VBOXTOOLS.COM website with the VBOX files to get precise results that will match under all situations.