# Engine RPM

> Acoustic Tachometer

Canonical page: [https://chrome-stats.com/d/id340401811](https://chrome-stats.com/d/id340401811)

## Overview

- **ID:** `id340401811`
- **Platform:** Apple
- **Type:** Apple app
- **Status:** Available
- **Publisher:** Real-Time Specialties
- **Category:** Utilities
- **Rating:** 4.00 / 5 (35 ratings)
- **Version:** 2.6
- **Last updated:** 2026-09-12
- **First published:** 2009-12-02
- **Size:** 3.14 MB
- **Data as of:** 2026-09-25
- **Store listing:** [Apple App Store](https://apps.apple.com/us/app/engine-rpm/id340401811)
- **Website:** [http://tunelab-world.com/tach](http://tunelab-world.com/tach)
- **Privacy policy:** [https://www.tunelab-world.com/privacyios](https://www.tunelab-world.com/privacyios)

## Description

Measure the RPM of an engine by analyzing the sound it makes.  Engine RPM listens to the sound of a running engine and uses advanced signal processing algorithms to extract the frequency of that sound and calculate the RPM.

This app is primarily for setup and diagnostics of engines.  After setting the the number of cylinders and whether the engine is a 2-stroke or 4-stroke engine, the app can work with any internal combustion engine, from diesel tractors to aircraft engines to motorcycles to chainsaws.  To use the app you must set an expected RPM range to guide the analysis algorithms to the correct RPM.  A real-time graph of the autocorrelation graph is displayed to help in troubleshooting and adjusting the expected RPM range.

The analysis requires a clear sound from the engine without excessive interference from extraneous sounds. Do not expect to read the RPM of an engine while other things are making too much noise at the same time.  The analysis also requires that the RPM be stable.  It cannot read the RPM of an engine that is rapidly accelerating.  For this reason, and because of the need for adjusting the expected RPM range, this app should not be considered a drop-in replacement for an operational tachometer.

Setup options include update periods from 93 milliseconds to 1.5 seconds, one to 12 cylinders, 2-stroke or 4-stroke, low-pass filtering, and signal clipping.  The overall RPM range is 400 to 90,000 RPM (although at any one time, the operational range is typically +/- 30% around a nominal expected RPM).  Precision is usually about +/- 10 RPM.

## Rankings

- #211,250 — Overall

## Review summary

Users praise Engine RPM for being cheap and helpful for tuning idle on various small engines when set up correctly, offering a non-contact way to measure RPM and useful features like logging and waveform display. However, many reviews cite reliability issues: readings can be inaccurate or missing, performance varies by engine and environment, and the app can crash or require careful configuration. It's not ideal for transient RPMs or electric motors, and refunds can be problematic.

### Pros

- Very affordable and good value compared to dedicated tachometers.
- Non-contact RPM measurement without attaching sensors or modifying the engine.
- Useful for tuning idle and RPM ranges on a variety of engines (snowblowers, mowers, chainsaws, motorcycles) with proper setup.
- Additional features like RPM logging and audio waveform display.

### Cons

- Unreliable or inaccurate readings across engines; frequent incorrect data and random jumps.
- Not universal—performs poorly on some engines (electric motors, cars) and can be affected by ambient noise and environment.
- Requires careful setup (engine type, sampling interval, range/harmonics) and is not plug-and-play for many users.
- Stability issues (app crashes, blank displays) and refund difficulties.
- Not suited for transient RPMs; works best with steady RPM values.

## Similar extensions and apps

- [SoundTach](https://chrome-stats.com/d/id6755052370) — 3.90 / 5
- [SoundRPM: Engine Tachometer](https://chrome-stats.com/d/id6787410484) — 5.00 / 5
- [Camera RPM Meter - StrobeLight](https://chrome-stats.com/d/id1583247436) — 2.20 / 5
- [Strobe Light – RPM](https://chrome-stats.com/d/id6747579407) — 2.00 / 5
- [Rpm Meter: Calibrate Turntable](https://chrome-stats.com/d/id6766424655) — 4.00 / 5
- [TurboTune](https://chrome-stats.com/d/id6761314616) — 5.00 / 5
- [Camera RPM Meter: Stroboscope](https://chrome-stats.com/d/id6785869103)
- [Frequency Generator & Analyzer](https://chrome-stats.com/d/id6771032203)
- [Strobe tachometer (RPM meter)](https://chrome-stats.com/d/id831460940) — 4.30 / 5
- [RPM Meter for Turntable](https://chrome-stats.com/d/id6473157917) — 2.50 / 5
- [Ellebogen](https://chrome-stats.com/d/id1611352289)
- [AcceloVibe](https://chrome-stats.com/d/id6747295321)

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Source: [Chrome-Stats](https://chrome-stats.com/d/id340401811)