Log Dyno vs JB4 PRO
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Log Dyno
This app analyzes your car's datalog files to measure torque and horsepower using your mobile device. It provides detailed analysis, recommends optimal gear shifts, and allows comparison of multiple measurements.
- Measure torque and horsepower from datalogs
- Virtual dyno analysis
- Optimal gear shift recommendations
- Compare multiple measurements
- Supports various datalog file formats
- Customizable vehicle data input
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Measuring your car's torque and horsepower has never been easier, now that you can do it with the help of your mobile device and this digital Dyno. You just need to open your datalog of a pull, and Log Dyno will do the rest. You can send your CSV file from your email, browser, or any app to Log Dyno which will Open the datalog from the app right away and give you a measurement, or you can save your CSV file to the Log Dyno folder in your Files app, for easy access from the in-app file browser. You can use any CSV or MSL file that contains RPM data which is needed to accurately measure Horsepower and Torque. From the torque curve and gear ratios, the app will also recommend optimal gear shift points for each gear to ensure maximum acceleration. This makes sure you know when to shift, so you always have the most possible power at the wheels. Corrections: ● Uncorrected ● SAE J1349 ● STD ● DIN 70020 ● ISO 1585 Power Units: ● WHP ● BHP ● PS ● KW Torque Units: ● LB-FT ● NM Either at the wheels or at the crank Compare multiple measurements! You can save each one of your Dyno measurements, and compare them, or just analyze them interactively. What datalog files can be used? ● JB4 ● MHD ● ProTool ● COBB ● MegaSquirt ● ProTool ● Bootmod3 ● and any other CSV file This is the easiest way to have your torque and horsepower measured with a virtual dyno using only your mobile phone and your datalog. You can see if your mods or tune work right away, and compare them. Log Dyno has been compared to multiple real life dyno sheets, and measurements were spot on, with multiple different vehicles How does it work? #1. Datalog your vehicle Take the log just like a dyno pull, in one given gear, from low rpm to high rpm. Try to avoid wheelspin as it can cause spikes in the graph. #2. Set up your vehicle data The dyno app requires some data about your vehicle. You’ll be asked to set values for the following: ● Car Name ● Weight ● Tank Capacity ● Tire Size ● DT% ● Drag Coefficient ● Frontal Area #3. Share the results! You can share your results right from the virtual dyno measurement page to basically any app or post it to any social network or email it. Of course, you can just save the results in your phone gallery too. How accurate is the dyno measurement? If you have set your vehicle data correctly, the results our dyno app gives will be the same as the results a real dyno will give you. Also, keep in mind that wheelspin may result in spikes in the graph. If you are unable to avoid it, you’ll still get accurate results, you just need to ignore the spikes. The best thing about our dyno app is that you can see right away how your mods work after datalogging. Now, you don't have to go to the dyno if you want to measure any small modification or just never had your car's power measured. You can see right away how your mods or tune work after datalogging. You can dyno unlimited times and unlimited vehicles for the fraction of the price of a dyno measurement. You have to set your car up, how much it weighs, its tire size, the gear ratios, and also what your car drag coefficient and frontal area are, which the app will help in determining. After specifying for which gear you had the datalog taken and specifying the driver, passenger, and possible cargo weight, you can open the CSV or MSL file. Based on your car data and environmental values, the app generates a torque and horsepower curve, which you can analyze. The app also points out the peak values, and you will be able to see at what rpm you made the most torque and the most power. If you have any questions feel free to send an email: profisoftgames@gmail.com
JB4 PRO
Integrate your performance tuner with your smartphone to adjust engine maps, view real-time data, and manage system settings. This app requires a specific Bluetooth adapter for full functionality.
- Change maps
- Monitor live engine data
- Record logs
- Manage fault codes
- Update JB4 firmware
- Smartphone integration
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Smart phone integration for your JB4 performance tuner to change maps, monitor live engine data, record logs, manage fault codes, update JB4 firmware, and much more! Note the JB4 PRO free app requires the JB4 PRO BT adapter and is not compatible with the JB4 Mobile BT adapter.
Screenshots
Verdict
The clearest difference is price: JB4 PRO at Free against Log Dyno's $13.99. JB4 PRO also leads on rating (4.4 vs 3.4) and review sentiment (50% vs 15%). Log Dyno's advantage is iOS requirement (9.0 vs 16.0). On ratings volume, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
JB4 PRO is free to download; Log Dyno costs $13.99 up front. Neither carries in-app purchases, so what you see is what you pay.
JB4 PRO holds the better App Store score, 4.4 against 3.4. Both are backed by a comparable volume of ratings — 10 and 14 respectively. Written reviews point the same way: 15% of Log Dyno's written reviews are positive against 50% of JB4 PRO's.
Log Dyno ships an update every 4 months, JB4 PRO fortnightly. The most recent releases landed on October 13, 2026 and October 1, 2026 respectively.
| Parameter | Log Dyno | JB4 PRO |
|---|---|---|
| Price | $13.99 | Free — better |
| Rating | 3.4 (10 ratings) | 4.4 (14 ratings) — better |
| Positive reviews | 15.4% of reviews | 50.0% of reviews — better |
| Number of ratings | 10 | 14 — better |
| Update frequency | Every 4 months | Fortnightly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 9.0 — better | 16.0 |
| Further details — not scored | ||
| Size | 128 MB | 22 MB |
| Age rating | 4+ | 4+ |
| Developer | Adam Keninger | Burger Motorsports, Inc |
Customer experience
Log Dyno
JB4 PRO
In-app purchases
Log Dyno
No in-app purchases
JB4 PRO
No in-app purchases







