Please read all of the following before buying this app:

The Engine RPM app is designed to listen to the sound of an engine and from that sound, calculate and display the RPM of that engine. However the app cannot determine the RPM if the sound is inadequate, or if the app has not been properly configured for that specific engine. The sound must be clear and steady and must not have too much noise in the background. The app works the best on engines with minimal or no mufflers, such as motorcycles, lawnmowers, leaf blowers, small aircraft engines, and the like. It works better at high RPMs than at idle. For cars with modern mufflers the app will not be able to measure the RPM near idle, or if the app is listening from inside the car with the doors and windows closed. The sound inside a modern car is much too quiet for this to work.

Engine RPM is not designed to be a replacement for an operational tachometer. For safety reasons it should only be used as a diagnostic and calibration tool for things like engine tuning or checking the calibration of a regular tachometer. Engine RPM is very accurate when it is able to lock on to the sound, often to within 10 RPM or better. The app is configurable for 2-cycle and 4-cycle engines and includes a generic configuration for unusual cases, such as a reduction gear. The normal RPM range is 400 to 90,000 RPM. For more information download the operations manual from:

www.tunelab-world.com/rpm