Anyone using this iPhone application? I couldn't resist for $15. For another $100 I purchased the TomTom windshield mount that has a GPS antenna internal (supposedly better than the iPhone's internal GPS).

I'm anxious to test it out soon.

 

Please post your results.

 

I have used lap timer pro on all generations of iPhone combined with the Tom Tom gps mount.

Without the Tom Tom mount and enhanced gps, it's a bit hit and miss with the individual gps readings and you do see it miss be start finish line, sometimes it's significant sometimes not. At VIR, a lap time of say 3:15 would be plus 1 second out at most, when the software does catch the finish line. Sometime it misses it altogether and you get those memorable 6 or even 9 minute laps. Most of the time it's roughly correct. Where you see the timing error is when reviewing video of a lap and take timing from that. So as a general stopwatch it's been ok. Also gives great circuit diagrams with corner entry and exit speeds but again they aren't that accurate because of the limitations of the iPhone gps receiver and frequency it samples at.

Things get better with the Tom Tom receiver but it's still not really accurate all the time. More readings for surebut it still misses the all important start finish line by a variable margin. The cradle is nice though and it's great to see a laptime on a very clear display when you want it. I mounted mine on the bottom left hand corner of he windscreen, nicely out of my line of sight up the road but easy to scan for when is got the inclination to look.

Also used the iPad version which didn't work at all and was a waste of money.

I bought a 3 camera setup racekeeper system and ran it at my last event. Night and day difference but you gt what you pay for. I reused the Tom Tom mount to just hold my iPhone/iPod touch which connects using wifi to the racekeeper system box. Superb having revs, laptime etc on the screen, which flashes at predetermined revs for upchanges.

 

glare is an issue with using the iphone in car

 

Never been an issue with mine, actually has worked very well even as a nav device using the Tom Tom cradle on the windscreen,

 

Were you using an iphone 4 w/ Harry's GPS Lap Timer?

 

Have done, yes.

 

O.K., back from a couple of track days with Harry's Lap Timer Pro for the iPhone. $15 on the App Store. I was about to invest 100x that amount on a pro system, till I stumbled on this find. But, with the addition of a $100 TomTom cradle, I get 2x the accuracy of the iPhone's internal GPS, plus a place to mount it. The app uses all the phones capabilities and is dirt simple to use. I get a video for each lap as well as lap times, fastest speed, average speed, G forces and lineal forces all around the track, all displayed on an accurate track map! It's freaking awesome! Granted, it's not up to the accuracy or reliability of a pro system, but it more than met my expectation for a lowly $115 investment. The author claims the lap times are accurate within 6 tenths of a second.

I did have trouble understanding the whole picture of use as well as the nuts and bolts. Documentation is not very helpful for the first timer. In 3 sessions at the track, I only managed to record a video of one entire session. Then I discovered that my GPS was not showing a signal - at all! I had mounted the cradle so the phone was a couple of inches up off the dash and maybe 6 inches to the right of the windshield center. I tested various spots for signal strength and ended up moving it near the top of the windshield and tucked to the right of the mirror. It did make it useless during driving, but I didn't really care at this point. I also had to start it before I belted in, since I wasn't able to reach it with my 6 point harness on. Gloves don't help either with a touch screen!

The other troubles I had were that I needed to tell it I was at a specific track. They have pre-defined tracks available for download. That seemed to be the key problem on getting it to record lap times. Then once I had it recording properly, the other issue I had was understanding how to access the data. Apple makes it so simple at times, that sometimes it makes it harder to understand. To see my speeds and Gs at various points on the track, I needed to zoom in on the track map (standard iPhone pinch gestures).

All in all, it worked pretty damn well for $115 investment! However, I do plan to buy a real camera and mount in on my roll bar. With it mounted the way it is on the windshield, I can't see the entire front of my car, nor can I see myself or my hands on the wheel (great learning tool!). But for lap times, I'm pretty darn happy. It didn't record every single lap accurately, but hey, you get a _lot_ for what little you pay. Big thumbs up.