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.
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Engine RPM FAQ
Is Engine RPM free?
Yes, Engine RPM is completely free and it doesn't have any in-app purchases or subscriptions.
Is Engine RPM legit?
🤔 The Engine RPM app's quality is mixed. Some users are satisfied, while others report issues. Consider reading individual reviews for more context.
The Tiny Tach tachometer I’ve been using in my small engine work wasn’t extremely expensive, but it’s finicky and difficult to use when I’m tuning something like a chainsaw.
This app, after a couple minutes glossing over the instructions, was almost intuitive to get to function. It will be really nice to be able to set this down and have both hands free to operate the throttle and adjust carburetor settings on equipment now. Large, easy to see display and controls plus other features I haven’t even gotten to will make my work SO much easier! Thanks guys, for all your hard work. I’m totally happy with the price!
Frustrating
I just want my 9 dollars back. Sick of trying to get this to work.
Got my snowblower working
Was able to dial in my snowblower RPMs no problem. I do think the app should have the cycle/number of cylinders option right on the Home Screen, I think that would help out. Also, would be nice if it had good enough response times to react to transient surges, really it’s only useful for steady RPM values. But overall, did what I needed for much cheaper than a small engine tach.
Smart, solid app, works every time
An indispensable shop tool
Works as advertised
The documentation explains exactly how this works, and what the limitations are. There are some big advantages too: low cost and no need to touch the engine.
I used this to tune my old rototiller engine. It took some experimentation on where to position my phone near the engine, but I was able to get a strong signal and confirm max RPM and idle RPM.
Pricey but works good.
This was a little more expensive that I would have liked but once I used it I would say it’s defiantly useful. Used it to check low and high speed of my lawnmowers and it’s right on. Just slide around the hint rpm as it’s running and it finds the speed right away. It’s also cool that you can also see the audio waveform. The app doesn’t look to fancy but as long as it keeps working with future iOS updates I’ll be happy.
Excellent Tool
This app worked very well to help me set the idle on my Royal Enfield 500cc single cylinder motorcycle. It picked up the “thump” of the engine immediately thus allowing me to fine tune the engine’s RPM to specification. 100% pleased!
Expensive and complicated but it works....
1- Read all the help pages beforehand; it’ll take you about 5-10 minutes but well worth it.
2- I used to set idle on a 2 stroke fuel injected motorcycle where the idle is critical: too high and the bike runs too lean, too low and it bogs down in low RPM starts.
3- At first I had it set up to sample every 3 seconds. That was too long. So I cut to 3/4 of a second and it was less of a hassle. I was able to guesstimate the current RPM’s at 1500, (actual was closer to 1700), so I set up the software that way, kept making small adjustments on idle screw until
I got it just right.
4- Logging the RPMs and times was a nice feature.
5- to get a 5 star price needs to come down materially or ease of use must improve significantly.
Overall I’m happy with this given the alternatives.
impressive
Allowed me to set my chainsaw high speed mixture. I was running 2k rpm rich, didn’t know how much power I was missing. Struggled a bit with idle reading, but that’s understandable because a 1-cylinder 2-cycle engine is lumpy at low speed. Increasing sample length did the trick.
Much better than spending $100+ for the Stihl tachometer. Impressive piece of software.
Works Great!
I used this to check the RPM on a couple of lawnmowers I have. I set the engine type, set the hint, and it found the correct rpm reading very quickly. I don't think I could go out and buy a tach for ten bucks or get it hooked up and working this easily.
