Review: Harry’s Laptimer “Petrolhead”

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Version: 20.0.3
Platforms: iOS and Android
– iOS: $14.99
– Android: $14.99
My Rating: 8/10

Pros: Easily customizable settings, straightforward autocross track setup, quick, detailed data overlay onto video from onboard camera

Cons: Data charts are noisy, menu navigation takes some getting used to, sometimes unclear if settings took effect, some portrait only views force all views into portrait until the screen is returned to portrait and then turned landscape

I’ve had Harry’s Laptimer, Rookie Edition, on my phone for some time but haven’t had the chance to make great use of it. I had the opportunity to try it on my excursion to the Nurburgring a couple years ago, but I couldn’t make the most out of it without a way to mount it in the car other than a cup holder. Now that I’m autocrossing regularly, I wanted to give it another shot and an upgrade to the Petrolhead edition: the first of two paid editions of the app. The main draw for this version is the video recording and data overlay capability not available in the free edition. The ability to review a run immediately afterwards seemed like it could be a great advantage, and it was. The app would begin recording data at GPS coordinates that I preset during the morning coursewalk and would conclude the recording at the finish line. The video starts a little late and ends a little early, so using it for evidence of the exact laptimes wasn’t possible, but it was very convenient to be able to “set it and forget it.” That’s not the app’s fault, because the resolution of GPS isn’t fine enough to get it exactly right. A “Standing Start” option exists for setting a staging area of the course rather than the actual start line, which I may try at the next autocross. After each run, the recording, with data overlaid, was immediately available. I could quickly pull the phone off my RAM mount and review the video a few times to make mental notes for the next run. You can check out the video recording here.

The video with automatic start and stop, plus data overlay, seems to be the most valuable part of the app. The data charts aren’t very helpful on a small screen, which makes the line and bar graphs seem cluttered and noisy. The ability to stream data from my Kiwi3 OBDII reader seems to have some promise. The app automatically overlaid boost, throttle position, and RPM onto the video,  which gave me some indication of where I was coasting and how high I was getting in the revs. There seemed to be a lag between the displayed engine data and the real conditions, but that is most likely due to the communication rate via bluetooth rather than the app itself. Other data is also recorded, such as MAP, air temp, and coolant temp, that is available when the raw data is exported from the app via e-mail.

160430 Data Screenshot
Exported data is output to a .CSV file. The data is recorded at 1Hz.

Using the app at a second event was more troublesome than the first. By defining an autocross track I believed that track would be the one that was kicked off when using the “Race” mode. The recording started at the right spot (different spot in the zMax parking lot than the first event), but would end at the GPS location of the first autocross. I noticed that the lap analysis status showed that the the track I defined at the first autocross was the one used, so I set the new track as the active track and tried again to no avail. I tried deleting the original track so as to remove any confusion, but for the remaining runs the recording wouldn’t end automatically. I have to do some digging to see what exactly happened, but it seems like there are a few things that could have been an issue. The most likely issue was the new-to-version-20 option to set a start line and finish line heading.

Is this a tip or a warning, seems like it may have caused me problems on Saturday…

When setting the option, a warning explains that setting a finish line heading makes the finish line definition more sensitive and thus more prone to error if the heading isn’t correct. I set the heading perpendicular to the finish-line gate, but the fastest way between the last turn and the gate was coming through the gate tangent to the last turn. It seems that I didn’t set the new track as the active track, and when I did get the new track activated in the run-recording mode the incorrect finish-gate heading caused the app not to recognize the finish gate. In the end I still had recordings of each lap because I could stop the recording manually, but it showed me that I couldn’t take the settings for granted and need to confirm what I’ve got set is what I’m looking for. With careful control of the settings and track definition, this app is a valuable tool for beginners for a low price. A more advanced tool may provide more insights for a more advanced autocross driver, but $15 for the ability to immediately rewatch your run to prepare for the next is a great deal. The app takes some getting used to, but once it is familiar it has the ability to be a very effective learning tool. After the race, reviewing the data to confirm temperatures and other parameters lends even more information to learn from and work with to make you and your car better racers.

One Comment

  • Thanks for sharing!

    When LapTimer detects a trigger, it will switch to the defining track automatically. Or the other way around: there is no active track to select as long as you use triggers and automated start / stops. The idea behind this is you load the tracks you drive regularly and don’t care about a selection afterwards. To whatever track you drive, LapTimer will switch automatically.

    For AXes, this concept can create problems because tracks defined will overlap each other (when using the same airfield or area). To work around, delete the User Track Sets shown in the first line below a AX track header (Lap List) for all AX sessions in the past. Keep only the User Tracks Set for this weekend. The old tracks sets and triggers are meaningless anyway – laps from these sessions are stored permanently already.


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