We recommend that you read this guide completely before your first use of PerfExpert. Automotive embedded measurement tools require rigor in their use, and PerfExpert isn't an exception to the rule! In case you have some difficulties using PerfExpert, please do not hesitate to ask for help by sending an email to This email address is being protected from spambots. You need JavaScript enabled to view it.



1.1 Calibration

1.2 Units

1.3 Trigger

1.4 Weather Correction

1.5 Smoothing

Car sheet

2.1 Create a new car sheet

2.2 Select a car and a setup for a test

2.3 Modify a car sheet

2.4 Delete a car sheet

Mounting the Phone


4.1 Measurement conditions

4.2 Perform the measurement

4.2.1 Timed Run (accelerations)

4.2.2 Dyno Run (power)


5.1 Read a result

5.2 Organize results

1 Settings

First, you must setup the app in order to calibrate the accelerometer of your phone, choose your units and many other things ... To do that, select the "Settings" tab (bottom right).


1.1 Calibration

A calibration of your phone accelerometer axes is required before your first tests. To perform a good calibration, you should ideally use a perfectly horizontal surface and a small box (like the original box from your mobile) forming a right angle with this surface. However, our calibration procedure allows a slightly angle surface. In the calibration screen, click "Start" and follow instructions on the screen. You'll have to stabilize your phone in 8 positions, and for each position a vibration (or beep) will occur telling you that you have to put the phone in the next position. For each of these positions, you have 10 seconds to properly stabilize the phone, and calibration will be done during the 11th second, seconds during which the phone must necessarily remain stable. At the 8th step, PerfExpert will ask you to stabilize your mobile in any position (preferably vertically inclined at 45 °) to verify the quality of your calibration. The calibration is recorded only if it is valid.


1.2 Units

The Units screen allows you to individually select the desired unit for each of the physical quantities used in PerfExpert.


1.3 Trigger

Trigger is the car acceleration "threshold" from which PerfExpert will trigger the test, after "GO" appear on the test screen. On first use, leave the default value.


1.4 Weather Correction

Power correction, defined according to a specific standard, can bring the power of your engine to what it would be in reference to atmospheric conditions defined by this standard.

Atmospheric conditions (temperature, pressure and humidity) can be automatically retrieved by PerfExpert on World Weather Online, using your location. When "Auto retrieving" is enabled, each time you enter the Dyno test screen, PerfExpert launch the retrieving if last weather auto retrieving is more than 2H old. When "Auto retrieving" is disabled (no internet connection or location service unavailable), you can manually enter temperature, pressure and humidity of the moment.

You can choose from five correction standards currently used in the world : DIN 70020, SAE J1349, JIS D1001, EEC / E, ISO 1585. The current correction coefficient is updated automatically according to the chosen standard and based on the current ​​temperature, pressure and humidity values.

1.5 Smoothing

Smoothing will determine how PerfExpert will process data acquisition. We recommend to systematically use medium smoothing, that is which we have set after serious study as giving the best results in most measure conditions. Other smoothings exclusively correspond to extreme cases. However, we indicate the uses for each smoothing :

  • Low smoothing (not recommended) : Only perfectly smooth roads & perfect mounting & power measurements only on the second gear
  • Medium smoothing (recommended): All types of roads from medium to perfect & excellent mounting but slight imperfection tolerated & power measurements on the second or third gear
  • High smoothing (reserved for poor measurement conditions): bad roads & imperfect mounting & power measurements only on the second gear.


2 Creating and selecting a car

Before measuring the performance of your car, you must fill its sheet, which will contain all necessary information for its identification and calculation of its acceleration and power. You can see all your recorded car sheets in "My Cars" screen.

You will notice some pre-installed car sheet examples, that help you to better understanding them and to show you their possibilities, including the ability to enter different "Setup" to help you organize your test results.


2.1 Create a new car sheet

To add a car sheet, press the "Edit" button in the upper right, then click the "+" button on the "New car" line that appears. It offers the choice between three sheets, corresponding to the level of information you have on the car to measure : "basic"sheet, “simplified” sheet, and “advanced” sheet. If you don’t have any information on your car, choose the "Basic" sheet, if you have only summary data, choose the "Simplified" sheet, and if you have all the data required for accurate measurements of power (dyno), choose the "Advanced" sheet. You may need to know that with a "Basic" sheet, you can only do accelerations (timed runs) : indeed, it is necessary to know a minimum of data to make power measurements, as they are only available with the "simplified" and "advanced" sheets. The table below summarize the situation :





Static losses


Dynamic losses

« Basic » sheet




« Simplified » sheet




« Advanced » sheet





Once you have selected the appropriate sheet type, you will then see a vehicle sheet pre-filled with default values that you will have to modify in order to match you car specs.

Once the sheet fully informed, validate it by pressing the "Done" button at the top right. Warning : if you go back to "My cars" screen without validating by first clicking on "Done", all the information entered will be lost.

You can enter up to three gear ratios, and an unlimited number of "Setup" that will help you group/organize results.


2.2 Select a car and a setup for a test

You can select a car for a test in several ways :

  • In the "Timed Run" or "Dyno" test screen by clicking on the toolbar button on the left, until the button title display the name of the car you want.
  • In the "My Car" screen by clicking on the desired car.

You can select a Setup for a test in several ways :

  • In the "Timed Run" or "Dyno" test screen by clicking on the toolbar button in the middle, until the button title display the name of the desired setup.
  • In the "Car infos" screen of the desired car, by clicking on the name of the desired setup.

Warning : results you find in the "Results" screen are those of the currently selected car.

2.3 Modify a car sheet

From "My Cars" screen you can modify a car sheet at any time. To do this, go to the sheet details by clicking on the blue disclosure button on the right of the desired car. Once in the "Car infos" screen, click the "Edit" button at the top right and you will see a small arrow appear on the right of each parameter of the sheet, telling you that can edit them.


2.4 Delete a car sheet

You can also remove a car sheet at any time by clicking the 'Edit' button at the top right of the screen "My Cars".

Remember that this is irreversible, and at the same time removes all results associated with this car!


3 Mounting the Phone

Perfectly mount the phone in the car, by following these three rules :

  • It absolutely must not move during the measurement
  • It must be submitted at least possible vibrations
  • It must be aligned with the direction of travel of the vehicle and not inclined laterally, but can be tilted vertically from 0 to 90 ° from the horizontal
Here is a diagram showing you the direction that should have your phone in the car :
Allowed phone mounting position in the car

The key point to remember is that the phone must be perfectly still during measurement, this is the most important point, and the only way to achieve it is by putting your phone in a suitable support, and making sure that this support is firmly secured in the cockpit. A simple (and free!) trick is to use as support the original box of your phone, and to jam your phone against the side walls of the box with wedges, and just put this box on the passenger seat. You must align it with the direction of travel, and chock it against the back : if you speed well in a straight line, acceleration will firmly secure the box against the back, and your measurements will be excellent! You can also, to ensure a good stability, stall in addition the box with heavy objects located on its sides and / or in front of it.


4 Test

Once your phone well secured in the car, and after checking the selected car you can perform Timed Run (0-60Mph, 1/8Mi ...) tests or Dyno tests by selecting the appropriate tab.

You can also select the appropriate Setup, so that the test result is automatically marked as belonging to this Setup. You can change the Setup for a result later so do not worry if you forgot to select the right setup before performing a test.


4.1 Measurement conditions

You have to measure on a road as plane and flat as possible, in a straight line, in the absence (or near absence) of wind, and with warmed and well inflated tyres (manufacturer pressure). And ALWAYS leave from a full stop, this is a FUNDAMENTAL point!


4.3 Perform the measurement

You're ready to perform the measurement : car well stabilized and stopped at the chosen starting point, make sure your foot is not on the brake and the hand brake is not pulled, clutch disengaged and first gear engaged, press the "Start" button located in the middle of the "Test" screen. The inscription "Wait" is displayed in red for a second, time during which you mustn’t move. Then the inscription "Go" appears in green : so you can leave whenever you want, the app will identify the precise moment of the start, and the timer will start immediately. In all cases, the timer (and thus the measure) will stop automatically after the first of the three following conditions met : 500 meters traveled, heavy braking, or a simple lift of the foot extended for more than 3 seconds. So you don't have to worry about anything else that your drive during the measurement, the app takes care of everything else!


4.3.1 Timed Run (accelerations)

Only one thing to do : crank up the speed, applying the best in you to blow up the clock (but not the app, in any case you will not succeed, even with 1000 hp!).


4.3.2 Dyno Run (power)

Select the gear on which you want to perform the Dyno measurement : to do that, click on the big button at the top right of the rev-counter until the gear number displayed is the one you want. It is recommended to perform Dyno measurements in 2nd gear unless the car does not have traction on this gear, in this case, choose 3rd gear. The 4th gear is to be used only in extreme cases : lite weight FWD car with very high power that doesn't have traction in 3rd gear.

Leave slowly in first gear, shift quickly to the desired gear, making sure to fall under the measure beginning rev (that is indicated by the flashing needle of the rev-counter). Then get full throttle up to the maximum rev. Once this maximum rev reached, put the car as soon as possible in coastdown (it is useless to continue to accelerate), and brake if you want : the app will understand in each case that the measurement has ended, and will stop the clock. We put the emphasis on the fact that you must cross the measure beginning rev at full throttle , and in the selected gear. Ideally, get full throttle 500 rpm before the measure beginning rev (exemple: at 1500 rpm for a 2000 rpm measure beginning rev).


5 Results

Once the measurement or the session is completed, you can see the results of your car. You can access to the "Results" screen by selecting the corresponding tab.

Results are grouped by Setup. You can create as many setup as you want in the car sheet and organize your results as you wish.
In the "Averages" section of the results list, the average of all results of a setup is done automatically for you when there are at least two results of the same type (Timed Run or Dyno) in the same setup.


5.1 Read a result

Click on the blue disclosure button on the right of the desired result (marked by the date and time of the associated measure) to see result details. The result type depends on the type of measurement performed (Timed Run or Dyno), you can access to a full screen graph of your result by clicking on the graph preview in the result sheet. By passing the finger pricking on the graph, you can see the values ​​of the curves at any point of measurement.

Dyno result sheets also display weather conditions, and car sheet parameters taken into account by the time of measurement.


5.2 Organize results

You can rearrange your results by moving them from one setup to another or deleting them. To do this, click on the "Edit" button at the top right of the "Results" screen : result suppression and moving accessories then appear for each of them.