Porsche and racechrono

[DerekB]

starting a thread where we can talk about and compare racechrono data from recent autoX. i just purchased the Dual Electronics XGPS160 and OBDLink MX+ that racechrono recommends. i should have the GPS this Saturday for LPR. i also figured out that i can add any video to racechrono as long as it's compatible with my phone/tablet. no need to buy a gopro.

thanks to Teddy and Himanshu for giving me their data from the last GGR event. racechrono does look to be quite helpful. i figured out how to add reference laps and use speed delta/time delta so i could compare the two drivers. i am able to see the slight difference in driving lines and figure out what worked the best. it looks like Teddy was able to get some great times through the first slalom section with Himanshu going 5-7 mph slower through the cones. Himanshu had great pace through the paint and breaking into the horseshoe but Teddy made the time back and more by using first gear and getting a straight shot to the next turn. it was pretty close after that with Teddy getting more top speed in the fast section but Himanshu made up some time by using the same line and going faster into the last turn.

great stuff. the software is a bit glitchy with the graphing of the time delta but the value is displayed on the bottom of the screen. the throttle position data should be useful too but that data from Himanshu seemed to be way off? once that is sorted out we could use longitudinal acceleration to figure out braking points and pressure.

looks like a great tool and for a $200 investment if it doesn't make me faster at least ill know why i'm so slow

here is my dash video and i'll have data soon

[mikey]

I've always wanted to try RaceChrono. I AX a 914 so getting any brake and TP info is impossible but I'd love to compare driving lines. Maybe I'll get one anyway and start trying to improve my times.

[tedaf]

Thanks for posting, Derek!

Here's my fastest run (I post all of my autocross and track video to my Youtube page):

Racechrono Pro was awesome. Everything just worked. There's a slight offset between the data streams that is probably fixable but I'm happy for now. As you noticed, my VBox Sport gave me GPS data of sufficient quality that I can actually trace my line choices as well as relative speed, etc., to see exactly where I gained or lost time from run to run or in comparing to others' runs.

Having data definitely helps. It reveals exactly what I need to work on next time, though I suspected this throughout the day: confidence through fast, decelerating sections (the last few corners of the course). What's interesting is that I would have perceived this as a relative strength before this weekend.

Unfortunately I can't post my data here - this forum doesn't recognize the default extension (.rcz). Is there any way around this?

[mikey]

Let me see if I can set the forum to allow posting of the data in (.rcz)

[mikey]

OK, see if it will let you post a downloadable rcz file.

Oh, and welcome to AXPADDOCK.COM !!!

Mike

[tedaf]

Thanks! I still see an error:

"Error

Invalid file extension: session_teddy_20190713_0911.rcz"

[mikey]

Strange. I'll look into it more later and get back to you

[DerekB]

i have been playing with the app some more and i am able to get some useful information without the GPS module. i was comparing my run with Himanshu using the time delta graph and i could see similar trends to the Teddy/Himanshu graph. he was slower through the first slalom section, fast into the horseshoe, slower through the fast stuff but made it back at the last turn but the speed and accelerometer data is way off. so, if someone wanted to just get the app they could get some use out of it if they were able to get someone with a GPS to share an accurate map/run with them.

i did some more research into the GPS modules and Vbox/Qstar both have built in accelerometer but the dual does not. the accelerometer data i got from the phone is garbage but racechrono says it uses the GPS data to get accelerometer data

"The lateral and linear acceleration is calculated from GPS only. You can also enable the real accelerometer from expert settings but that is not calibrated nor rotated."
are you guys using the expert setting?

i think the accelerometer data is useful and it looks great using the Vbox, i just hope i get similar results using the Dual GPS. if not i can return it and try Qstar. it should be fun to try out this weekend.

[tedaf]

That's interesting. I'm not using the expert setting and was wondering how the accel data was automatically aligned. I'm happy to leave it as-is, I think, at least for now.

[KenJ]

This is submitted respectfully... I know things have opened up with some AXs these past seasons, so, it's really best not to show the speedometer on your videos..... especially this last one. We won't have Alameda much longer, but let's not give them reason to curtail things early.

Have fun,

kj