edub

I'm trying out a DAQ setup using a Racebox Mini (for 25Hz GPS), Race Chrono Pro (https://racechrono.com/) for timing and track maps, and a to-be-determined ODBII data logger.

With a 2021 718 GT4, what works well for capturing ODB II and transmitting it over Bluetooth?

Race Chrono Pro has suggestions for ODB II systems but I found a limited amount of experience on those vendors forums for Porsche vehicles.

```
On Android:
OBDLink LX Bluetooth, MX Bluetooth or MX+ Bluetooth: Super fast update rate, on a modern car up-to 50 Hz. Has a power saving feature, so it won’t drain your battery if you leave the adapter connected, and a physical button for pairing as a security measure.
OBDLink CX Bluetooth: Not as fast, and does not support as wide range of vehicles as the other OBDLink models, but more affordable and connects using Bluetooth LE.
Carista Bluetooth OBD2: Affordable alternative, update rate at 10-15 Hz, connects using Bluetooth LE.
```

Thanks!

SANSPDK

I use the MX+ Bluetooth with my Racechrono setup on my 2020 GT4. I have no issues with it other than occasionally having to reconnect it to the phone at the beginning of a track day. Seems to work fairly well.

edub

Thanks - what data are you getting out of the MX+? I have heard that little to no information is available without additional PID's.

SANSPDK

This is a sample of what I usually pull with RaceChrono. The only other thing I use is a VBOX GPS.


There are some other data points but I don't worry about them as much. Really the only items that I would like that I cannot get without the PID's is the gear selection and brake data. That will be my next step as I progress in my abilities.

ProCoach

Pretty video but it doesn’t seem like the values track what is happening. I see the throttle go to 100% for a few seconds, the speed not really rising much from about 60 near the end and then when the throttle goes down (lifting off) the speed changes quickly. Odd.

SANSPDK

Good observation. I posted that as an example of what data I pull. This is the first year I have done any sort of HPDE so this was like many of my other sessions which were basically me focusing on how to drive a line. I'll worry about shifting next year

ProCoach

I think video is the best tool for starting out. Basically a validation that you're doing what you think you're doing and to share with others for tips and feedback.

It's SUPER important to have this because about 80-85% will be as you remember it, 15-20% will be different from what you remember. The latter is what you focus on next session or next event at that track.

If you're consistent, that's the goal. If you're not accurate, or not in the same place laterally for every foot forward you travel over several laps, or missing apexes, or late on the throttle (validated by AUDIO, not what is showing on the dial from the high-latency data), then fix that.

The data overlaid, while interesting, is not useful for validating what you're actually doing with your feet nor is it an accurate reflection of the speed at any particular point on the lap or circuit.

I base this observation on a couple decades of coaching people using video and data overlaid on that video full-time. Just don't put too much stock in the throttle, RPM or speed readings on your videos.

lordvonpineapple

I am writing an iOS app that for my 997.2 which uses commodity OBD2/Elm327. I have identification of manual gear selection working in real time.

Last_935

@lordvonpineapple Any updates on this?

lordvonpineapple

Sure. I have been working hard on the mobile app itself, the cloud backend for all the data, and also a web front end. The App records lots of useful data points - everything that comes over standard ODB2, plus I enhance that with data from the phone (GPS-based location and speed, Acceleration/Braking and Cornering G forces, Elevation) and also stuff from weather services (local temps, weather, barometer etc). I have implemented algorithms that can also derive further data points from the raw data (i.e. MSA-corrected air/fuel horsepower from MAF + air temp + air pressure + humidity, manual gear detection etc. I have implemented some support for Porsche-specific protocols over the ODB2 port, so I can read data points like over revs from ECU, and other items that don't come over the standard ODB2. I am looking to conduct a private invite-only beta later this year. When I am ready for that I will start a post here on Rennlist for sure.

edub

von - add exlap support to your app please https://github.com/edub0/EXLAP

lordvonpineapple

edub, that looks cool I wasn't aware of it. Thanks for sharing.I will definitely take a look at supporting that. Ive been working hard on the best data architecture to support the types of functionality i want to offer at scale to a reasonable size user base. My app will do a lot of comparative analytics and statistical stuff. It will come in a 'Road' flavour and a 'Track' flavour, but the underlying data architecture and back-end is common. The UI has a different focus for Road (Trips and Segments) vs Track (Sessions and Laps). Underneath those concepts I have a Dataframe concept which is a grouping container for aggregating the data points for a short period of time. I also have to deal with the difference in frequency or the different data points. GPS and Accel from the phone is fast, but ODB2/ELM327 has its bandwidth limitations, which I work around dynamically. All fun stuff.

Last_935

@lordvonpineapple thank you for the update. I look forward to checking it out once it's available. Two questions: 1) Have you considered the integration of an external GPS with a faster refresh rate like RaceBox Mini (25Hz) or Dual XGPS160 (10Hz)? 2) Although more expensive, have you thought about utilizing an ODBLink MX+? My understanding is that it has a refresh rate of 50Hz which would eliminate the bandwidth limitations of the OBD2/ELM327. Somewhere I read that each channel utilizes around 5Hz of bandwidth and that cheaper Bluetooth OBD2 adapters have a refresh rate of 6-10Hz.

lordvonpineapple

I will look at integration with popular hardware at some point. Initial release is for commodity bluetooth ODB2 adapters plus phone for GPS etc. Phone GPS is already much faster than ODB2. I have a collection of about 10 different OBD2 adapters, all work fine. I have not seen much difference in behaviour in adapters (the limit is in the way the car responds not in the hardware of the bluetooth adapter), but will do a full report before release. I would be interested to understand the performance difference of an external GPS box vs whats available in a phone.

edub

You may just have to test that to really figure it out. When I used to turn laps with a 5Hz GPS logger lap times were always within +/-0.1 second of a AMB transponder time, and more than 50% of the time they were less than 0.1 of a second off the transponder time. I imagine the 25Hz GNSS location systems will be improved over that.

I have not looked lately, but in 2018 phones were generally 1Hz for their location updates. Probably still pretty accurate, but I would protest the results from any competition in which 1Hz GPS signal was used to measure results in motorsport