RPM Boss

RPM Boss tells you how fast an engine is turning by listening to it.

Point the phone at a running engine and press Start. The tachometer reads live, needle and number together, for as long as you keep listening. Nothing is recorded and nothing is kept.

When you want a number you can check, record a few seconds instead, or open a clip you already have, crop it to the clearest stretch and press Calculate. You get one figure and the waveform with every combustion the app counted marked on it, so the reading shows its working.

It reads single-cylinder engines, two-stroke or four-stroke, across the range: idle, part throttle, near the redline. What it needs is a steady engine and not too much noise around it.

LIVE TACHOMETER
* Press Start and read the dial while the engine runs
* A needle, the figure underneath, and the sound drawn as it arrives
* The screen stays awake while it listens, so it will not time out mid-measurement
* Nothing is recorded in this mode and nothing leaves the phone
* Set where the dial ends and where the redline begins, to suit your engine

MEASURE FROM A RECORDING
* Record up to 10 seconds in the app, or open a WAV, MP3, M4A, AAC or OGG file
* Watch the sound draw itself while the recording runs
* Drag the crop handles to the cleanest stretch
* Play back what you selected before you measure it
* Press Calculate for one RPM figure and the count of combustions behind it
* Every combustion is marked on the waveform
* Save a recording as a WAV file if you want to keep it
* Add an optional expected range when a reading looks doubled or halved

SET IT UP FOR YOUR ENGINE
* Two-stroke or four-stroke
* Where the dial ends, and where the redline starts
* How quickly the needle follows
* Light or dark

BUILT TO STAY OUT OF THE WAY
* No ads
* No accounts and no sign-up
* No internet permission, so the app cannot send your audio anywhere
* No analytics or tracking of any kind
* Nothing is uploaded: audio is analysed on your phone and then forgotten
* Works offline, always

WHAT IT IS NOT
This is not a diagnostic tool. It reads one cylinder at a time. A multi-cylinder engine, an engine whose speed is still changing, or a noisy place will not give you a number worth trusting.

Available in English, Spanish, French, Portuguese, Indonesian, Malay, Filipino, Bisaya, Swahili, Vietnamese, Thai, Hindi, Bengali, Urdu, Russian, Ukrainian and Armenian.

Privacy policy: https://mby4m.github.io/legal/rpmboss/