Engine RPM

Engine RPM

Acoustic Tachometer

35 ratings
64 reviews
$8.99

Details

  • Released
  • Updated
  • December 2, 2009
  • October 2, 2026

Features

Engine RPM screenshot #1 for iPhone
Engine RPM screenshot #2 for iPhone
Engine RPM screenshot #3 for iPhone
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About

Analyze engine sound to calculate RPM using advanced signal processing. Ideal for engine setup and diagnostics, it supports various engine types and provides real-time feedback for accurate readings.

βœ“Acoustic RPM measurement
βœ“Engine sound analysis
βœ“Supports 2-stroke/4-stroke engines
βœ“Configurable cylinder count
βœ“Real-time autocorrelation graph
βœ“Adjustable update periods
βœ“Low-pass filtering
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What users say

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What's New in Engine RPM

2.6.1

October 2, 2026

Fixed a bug that prevented the saving of the number of cylinders when the app is closed.

Charts

Top Paid

πŸ“ˆΒ 73+10

Utilities

This app rose +10 positions in Utilities chart.

Last updated on October 13, 2026.

User reviews

Helpful

Like others I used this to measure rpm on my lawnmower. It helped me diagnose a problem and saved me a trip to the repair shop. Worth the fee in my case - saved me some time and money.

Did not work

Needed to monitor and adjust the idle on my motorcycle.
Did not once register a live rpm reading.
No matter what settings I adjust it still held the same 4 digit reading in red.
I placed my phone even directly behind the exhaust and the number read the same even tho I raised and lowered the actual rpm.

I had hoped from the review I read that this would be my savior but instead just a loss of money.
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Fonctionne super bien

Il faut bien faire ses rΓ©glages avant !

Can’t save config

Good app to troubleshoot, but after find the good parameter the app don’t have option to save parameter

Engine RPM

I just replaced my old mechanical tachometer on my Isuzu 4 cylinder marine diesel on my sailboat with an electrical one driven thru the alternator and Balmar MC 618 regulator. Following the instructions on the tach and the RPM app it all danced perfectly and accurately! Simple accurate!

Developer apps

User experience

🐞

Reported Bugs

12 issues

Does not register live RPM readings

Bug

Displays incorrect or random numbers

Bug

App opens then closes immediately

Bug

Blank display or flashes incorrect data intermittently

Bug

Cannot get consistent readings

Bug

Does not work on specific devices (e.g., iPhone 6)

Bug

E-motor measurement not possible

Bug

Readings are not accurate

Bug

Cannot get a reliable reading

Bug

Randomly skips between significantly different numbers

Bug

Generates random numbers

Bug

Does not recognize sound correctly

Bug
✨

Requested Features

5 requests

Save configuration settings

Feature

Option to display cycle/cylinder count on home screen

Feature

Improved response time for transient surges

Feature

Simplified or automated setup process

Feature

Auto-scaling graphical display for easier harmonic matching

Feature

FAQ

What does Engine RPM do?

Engine RPM measures the revolutions per minute (RPM) of an engine by analyzing the sound it produces. It uses advanced signal processing to extract the engine's sound frequency and convert it into an RPM reading. This makes it useful for engine setup and diagnostics.

How accurate is Engine RPM?

The app typically offers a precision of about +/- 10 RPM. However, accuracy depends on factors like engine sound clarity, lack of interference, and stable RPM. It's important to set an expected RPM range to guide the analysis algorithms for optimal results.

What types of engines can this app measure?

This app can work with any internal combustion engine, including diesel tractors, aircraft engines, motorcycles, and chainsaws. You can configure the number of cylinders and whether the engine is 2-stroke or 4-stroke to tailor the analysis.

Is Engine RPM a replacement for a physical tachometer?

No, this app should not be considered a drop-in replacement for an operational tachometer. It requires stable RPM and a clear engine sound without excessive interference. Adjusting the expected RPM range is also necessary, making it more suited for setup and diagnostics than real-time operational monitoring during rapid acceleration.

What are the setup options for Engine RPM?

Setup options include adjustable update periods (93 milliseconds to 1.5 seconds), setting the number of cylinders (1 to 12), specifying 2-stroke or 4-stroke operation, enabling low-pass filtering, and signal clipping. You also need to set an expected RPM range for the analysis.