Go faster in autocross | The apps, sensors and traces you need

One of the keys to going fast is knowing how fast you’re going, and one of the best ways to know how fast you’re going is with some sort of data acquisition system. For road racers, data acquisition has become more or less standard. 

But where does this leave autocrossers? Has the democratization of data for the track crowd rubbed …

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I've had success with TackAddict (free). I also use it to import obd2 data into my videos through Racerender.

as long as I remember to turn it on. I mostly compare two runs in a playback, and see where I'm gaining or losing time, trying to remember what I did different. The white dot is a lap, and the blue dot is a lap where I was slower.

edit: the lap time isn't a true lap, since I don't setup the segments ahead of time, so it counts my return to staging as part if the lap. This is 22 Solo Nats Crows day 1.

Im a 14 + year subscriber but can't access articles nor find detailed instructions how to.

I used TrackAddict with an external OBD reader and Bluetooth GPS. I felt the combination was unreliable at autocross since I had to manage the connections. Two years ago I switched to Solostorm and RaceCapture. The built in data and gps integrates well for me and has been great for comparing data with co drivers. 

bvanepps said:

Im a 14 + year subscriber but can't access articles nor find detailed instructions how to.

Not sure whether this helps, and I don't know whether there's an index or tree or something somewhere, but here's at least some kind of interface to article access:

https://grassrootsmotorsports.com/articles/

David Elfering said:

I used TrackAddict with an external OBD reader and Bluetooth GPS. I felt the combination was unreliable at autocross since I had to manage the connections. Two years ago I switched to Solostorm and RaceCapture. The built in data and gps integrates well for me and has been great for comparing data with co drivers. 

I used SoloStorm quite a bit and liked it a lot, but I've noticed that I've been favoring ApexPro as they continue to ad features. Ultimately I think it's just my familiarity with the OSX devides that makes me lean Apex, but SoloStorm is a powerful and versatile suite of software for a great price.

TrackAddict has worked best for me in Autocross and Rallycross of the phone apps but can still be flaky whether it actually starts and stops timing at the start finish line. Harry's and Racechrono have been worse in my opinion.

I just picked up a Racebox mini to try out which has very accurate GPS at 25 Hz along with built in G and pitch/yaw/slip sensors. Some apps can use the just the GPS data (Harry's and RaceChrono but not TrackAddict at this point) but it seems like to use all of the built in sensors the Racebox app is the only way to go and it is not setup well at the moment for this use. You can setup a course for timing autocross but it requires you to drive the course at > 10 km/h and press buttons at the same time on your phone to set Start/Split/Finish points. That is not practical to do at one of these events or an accurate way to define the course. I'll be using it this weekend at Mosport though and I think after that sending them some feedback on the app to hopefully get some improvements.

Edit - Just found where I can create custom courses without the device connected in the Raceox app using google maps so it should work, I'll see how it goes when I finally get to an autocross!

So as a follow up to my post, I've now used the Racebox mini at Mosport and a local autocross and I'm very happy with it. When using it with their app all of the data is provided by the mini so the location of the phone does not matter which can be nice, I really wasn't interested at either event in the live timing so the app was opened, connected to the device and then thrown in the centre consol/glovebox.

On the track it worked as it should with accurate timing, g and yaw readings with the laps and sessions displayed in an easy way. You can easily compare one lap to another but it is based on time alone, in Circuit tools for example you can compare on position which is nice to see exactly what your speed delta is around a track. 

At the autocross I think I was most impressed as I've had a lot of issues with other phone based laptimers not starting, not finishing or doing nothing. With the app I setup a custom "open" circuit (rolling start with a different start and finish, "hillclimb" gives you a standing start that you hit go when you are staged and it starts timing on acceleration) as the start beams were out 30 ft into the course, up to 3 splits and the finish (set using my phones GPS position as I walked the course). The timer worked EVERY RUN which is a first for me, not only that but the timing was within a tenth of a second of the official timing so I was blown away by that. Again you could easily compare two runs to each other and see how you did around the course with a speed or G trace which is exactly what you need. The way the course is displayed in the app also shows a cornering G line as well which is interesting as you compare runs.

The app also uploads to their website automatically, the analysis on there is a little disappointing as it does not allow you to compare runs so I've only found it useful for downloading the data (.csv or .vbo) to use elsewhere but that is easy and painless.

So to sum it up I'm pretty happy with it for $179, it's a super accurate GPS and IMU running at 25 Hz, the app does what it is supposed to, it's worked every time I have remembered to open it and connect (which is easy). I just wish it could take in OBDII readings to the app as well for my newer car.

In reply to adam525i :

I hadn't heard of the Mini before, so I went and looked it up. It seems really impressive! Also, they've got the protocol documentation available, so it'd probably be pretty easy to hook it up to a custom phone app that integrated the OBD2 bluetooth data. It'd just take some programming to do it. To that end, it's gonna be pretty easy for them to add that feature in the future, since they're 90% of the way there already. Just needs an app update!

I've been toying with Harry's and my own DIY GPS solution for AX/RX data, but having a box with everything in there including the gyro and accelerometer is really an impressive package. I know what I'm asking for at X-mas!

I have run TrackAddict on an iPhone and on an Android and have had good success. It works pretty well with just the phone's data, but I run an external GPS and a VeePeak OBD2 reader and that seems to make starts and stops more reliable. I usually set the start and finish lines manually. The only downside to me is that you can't export a video with data to YouTube from the phone. You either let it play and do a screen capture, or you have to export it to the RaceRender software, which is pretty good IMHO, but still an extra step. You can combine videos pretty easily in RaceRender, I use the phone's camera but sometimes add in an external GoPro. 

As of now, I just share videos with friends and ask for feedback, but I will be reading this article to see if I can actually use the trace data to go faster! 

adam525i said:

You can easily compare one lap to another but it is based on time alone, in Circuit tools for example you can compare on position which is nice to see exactly what your speed delta is around a track. 

Just a quick follow up, in the app you can compare two runs/laps based on position rather than time into the run, once again I just had to find the option. 

I think the only disappointment is now that I have consistent data I know how much time I left on course at the end of the day taking the best from each run lol.

In reply to pinchvalve (Forum Supporter) :

I have Track Addict on iPhone, if you are on the review video screen the blue button in the lower right corner will bring up an export video and data dialog box.  From there you can export the video to your photo album on your phone.  Then share it to YouTube or other website.  Good luck!

Autocrossing: I've been using SoloStorm for several years, in a fairly cheap way.  There are two Scosch magnet stands on my dash (just one vibrated the video too much) that hold a tablet.  The tablet receives GPS from a 10Hz puck on the roof, the very limited OBD data from a dongle (no braking info, only throttle and RPM in a year 2006 car), and uses the tablet camera for lap video, and tablet sensors for their estimate of G-loading.  It can even integrate a separate GoPro but I got some setting wrong and it now doesn't talk to the GoPro.  The stands look funny but hardly anyone rides in the car other than autocrossers, so who cares.  My video still vibrates more than I like but it's usable.  The G-loading isn't truly calibrated but it's consistent from event to event.  With full Street Touring suspension mods and top 200 TW tires, the max G's come back at 1.2 on good asphalt and 1.3-1.4 on Crows Landing concrete, probably the grippiest in the country.  I'm sure that the well set up 370Z with 50mm wider tires is probably pulling another 0.1 G's.  The one negative about this setup is that the tablet is up in the sun and overheats, so I have to shade it between runs and run a/c on defrost; on the 100 degree plus days it sometimes overheats before one run is over!

I'm intrigued by the idea of using the speed traces, but the way I have always analyzed my runs is using SoloStorm's own course segmentation, and comparing each section of the course by elapsed time.  Then I can see where the most improvement could be obtained. 

The major problem with ANY data in autocross is that one doesn't get a comparison until earliest after the second run.  For SCCA National events, that's kind of late as you only get three runs.  You get much more value if you have a co-driver as you instantly have twice the runs to compare.  For local events that have four, five, even eight+ runs with smaller marque clubs, there is much more room to learn from your data.  I'm not top notch at being able to analyze my lap in my head so the data give me more real-world feedback.

With this rig, it's a $100-ish tablet, $85 QStarz GPS, $135 OBDLink MX+ (those have gone up, the cheaper ones may work adequately), and whatever SS is going for these days, sounds like $220.  You could use a phone but playback is harder to see, and you have to attach it somehow.  This is as much as two tires cost. 

The speed trace idea is interesting, but auto-x is all about shortest time, and often different course lines will result in higher speeds but equal or slower times.  SoloStorm immediate playback shows multiple car laps simultaneously so you can see  where the car is ahead from a particular run.  When I carefully mark the start and finish by carrying the tablet and GPS and initializing the spots during course walk, the SS time is generally within a couple of tenths of the timer results.