My Region is doing a track day time trial Saturday.
They don't do transponders; I'll need to use my phone to show my times.
I need something simply; someone suggested I could use Hot Lap and just stick the phone in my pocket.
My Datsun doesn't really have a place to mount the phone well (cuz race car)
Also note I'm technology incompetent.
I like RaceChrono Pro, I just zip tie my old phone to the roll cage at the start of the day and let it charge off the cigarette port
If you want reasonable accuracy with the phone timers you'll need an external gps, as phone GPS units only update around once a second. I use a Garmin Glo, which updates 10x a second connected via Bluetooth. They were ~$100 when I got it a few years back
I use Harry's Lap Timer on both Android and iOS. You need a reasonably stable mount so the phone does not fly around, but back pocket should work. Phone GPS isn't going to be very accurate as mentioned so for anything serious, you really need an external GPS receiver as already mentioned.
Apex pro works well as does Track addict but none will work worth a crap in your pocket. They will need access o GPS and your pocket isn't very accessible.
I've had good luck with RaceChrono. I had to slightly adjust the start/finish line to correct a few double laps, but otherwise it worked well.
I think we have a magazine story that at least partially covers app timers. Let me see if I can track it down.
Edit: Found it. I hope it helps:
Go faster in autocross | The apps, sensors and traces you need
How do you qualify and race a car without a lap timer with predictive lap capabilities?? :)
Highly recommend at least an AIM Solo for anyone who races or does time trials.
Thanks guys this is the region's first time trial.......it's a bit of an experiment. It is a mix of track day / time trial.
As for the times I just need to post a time, any time. I don't think there is even anyone in my class as I'm one of the few race cars and so I'm not worried about it being accurate to the 1000th of second.
I may try to do a dash mount but my car as an aluminum dash.
Here's my experience with TrackAddict. I rigged up a foam block to hold my phone flat in a pocket behind the handbrake:
https://grassrootsmotorsports.com/forum/grm/trackaddict-users-best-phone-orientation/208168/page1/
In reply to GameboyRMH :
I have a spot where the passenger seat was that would probably allow me to bolt a padded pouch of some sort.
Tom1200 said:I have a spot where the passenger seat was that would probably allow me to bolt a padded pouch of some sort.
Most dedicated track logger use accelerometers to supplement the GPS signals. I don't know if phone apps do the same thing or not, but the phone has the sensors so I wouldn't be surprised.
If so, then you probably want a rigid mount, not a padded one. Can you get one of those brackets designed to let you use the phone while driving? If so then that's probably what I'd do (although I'd bolt it down rather than use a suction cup on the windshield.)
codrus (Forum Supporter) said:Tom1200 said:I have a spot where the passenger seat was that would probably allow me to bolt a padded pouch of some sort.
Most dedicated track logger use accelerometers to supplement the GPS signals. I don't know if phone apps do the same thing or not, but the phone has the sensors so I wouldn't be surprised.
If so, then you probably want a rigid mount, not a padded one. Can you get one of those brackets designed to let you use the phone while driving? If so then that's probably what I'd do (although I'd bolt it down rather than use a suction cup on the windshield.)
TrackAddict will use the accelerometers so you do want the the mount to be pretty rigid. I used some craft foam, which is a firm but incredibly messy material, I would recommend using waste styrofoam instead, the craft foam wasn't cheap either...
codrus (Forum Supporter) said:Tom1200 said:I have a spot where the passenger seat was that would probably allow me to bolt a padded pouch of some sort.
Most dedicated track logger use accelerometers to supplement the GPS signals. I don't know if phone apps do the same thing or not, but the phone has the sensors so I wouldn't be surprised.
If so, then you probably want a rigid mount, not a padded one. Can you get one of those brackets designed to let you use the phone while driving? If so then that's probably what I'd do (although I'd bolt it down rather than use a suction cup on the windshield.)
If all you care about is lap time, that doesn't matter. Just tape/ziptie/whatever it somewhere vaguely in sight of a window and it'll be fine.
Just a remember that your phone GPS is likely only 1 Hz. Meaning it samples once per second. A second is a LOOONG way at racing speeds. This can easily be fixed with an external GPS. Connects to the phone via Bluetooth, and will operate at 10 Hz or more. . Runs about $100 or so. It will make a big difference if you start to plot your locations.
Track Addict user here. I mounted the phone on a suction-cup windshield mount, and it works fine. The video is a little bit jiggly, but the timer function works well.
wake74 said:Just a remember that your phone GPS is likely only 1 Hz. Meaning it samples once per second. A second is a LOOONG way at racing speeds. This can easily be fixed with an external GPS. Connects to the phone via Bluetooth, and will operate at 10 Hz or more. . Runs about $100 or so. It will make a big difference if you start to plot your locations.
I've found TrackAddict times to be within a hundredth of transponder times even with 1Hz GPS. It has a smoothing/averaging algorithm that works pretty well for that, but it clearly doesn't do anything for speed or heading data.
I have used Harry's Lap Timer for years without much to complain about. I bought a separate GPS but stopped using it ages ago, its just one more thing to worry about. Times are within a few hundredths of transponder times, I'm not good enough to care about that small of a difference. Predictive time is great (and hugely useful).
One thing Harrys/phones haven't done well for me is video recording. w2w I'm required to run a camera, but during the summer every phone I've had will overheat. Waiting on a Catalyst to show up to solve that (GoPro has been a giant PITA).
I had an epiphany this week reading this thread, I was jealous of all the new cars with the fancy OBDII ports to get this kind of data/data overlay and I really like my Haltech ECU, completely forgetting that it too has a canbus system; in comes the easy button hero!
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