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Measure RPM with Android app

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4.5K views 5 replies 5 participants last post by  fhusted1977  
#1 ·
A few weeks ago I asked for volunteers to test the iPhone version of this app, and that is going well. Now the Android version is ready for testing too. This is an update to an existing Android app called "Engine RPM" I have in the Google Play Store. It listens to the sound of the engine and applies some advanced signal processing to extract the frequency of the engine and calculate the RPM. Recently I improved the processing by adding a software clipping option and low-pass filter to reduce noise interference. You could use it to check the accuracy of a hard-wired tachometer, or to adjust engine settings on engines without a tachometer. Think of it as a piece of diagnostic equipment, and not as a replacement for a full-time operational tach. To sign up for closed testing of this Android app, send me your e-mail address in a conversation and I will send you a link for installing the app and a promo code so that you can download the app for free. If you go straight to the Play Store and find my app without being entered as a tester then you will only see the old version, since the new version is not released yet to the general public yet, which is why I am asking for testers. Thank you for you help.

-Bob Scott
Hopkins, MN
 
M
#3 ·
Installed the app (thank you) and used it to measure the rpm of my single Techumseh on my tiller, the twin Kohler on my ZT and my 8 cyl Ram 1500. Both small engines worked great and appeared to be accurate and were easy to set up. I tried to use my photo tach for a comparison but it took a bad one, as did I and it got relegated to the trash can.
The Rams' reading, according to the truck tach was off by 200rpm on the high end, the reading was taken under the hood (which probably picked up other mechanical noises) and directly at the exhaust. It was quite finnicky getting the settings correct to get a proper reading. In all fairness, I would never use the app for an 8 cylinder engine and just tried it on a whim as I had to move the truck out of the garage.
Next I'll try it on my three cylinder diesel Iseki tractor when I have it out.
Overall, I'd recommend it as a good app.
 
#4 ·
So, I did some testing today on the X728, NY322 and Tville322. I took the results that can be emailed from the log and did a little PowerPoint finagling on the file and was able to graph the results of one low RPM test on Tville322: (the log had 4 results in it for this test) and I added the average line in by totaling and dividing by 4: The idle RPM for a 322 is around 1300 RPM, not sure if this is reflective of the app or the actual RPM as I have no tach on the 322 to check it against. If nothing else given the environmental factors limitations of the app to adjust and capture at the low end of RPM (he states that in the documentation) this was fairly consistent over the four results. I'd have to put a tachometer or photo tachometer on the 322 to validate these readings.

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Here are the screen shots as they appear on the app (moment in time so only one result):

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