Acoustic Tachometer (RPM)

★★★★★ This acoustic rev counter works very well for me in a Nissan Micra, held in a cradle on the dashboard.. Random numbers come up when the engine is off; when started the rev counter locks on to the sound and registers what seems very reasonable .numbers, judging by results from an OBDii reader. Nice clear readout; Installed it on an old HTC smartphone not used for anything else. Running wiring to a conventional rev counter from the engine would be difficult and messy. This is much simpler and well worth trying..

★★★★★ interesting app. pretty good, not exactly 100 percent accurate, but close enough to get the job I was working on done. my brother and i were timing the engine of an old 280z, the tach in the car didnt work, this app was actually a huge help. I believe the option for 2 stroke and 4 stroke are backwards. was accurate as possible with the 2 stroke setting, and was way off on the 4 stroke setting. regardless not bad at all.

★★★★★ Im trying to conserve fuel after Hurricane Ida. Tried a bunch of other useless apps before I found this one. It worked great for setting the ideal RPM of 2250 on my generator. Thanks so much!

★★☆☆☆ Tried it to calculate the engine revs of a vintage low speed diesel didn't work out

★★☆☆☆ Doesn't work at all. Single cylinder 4 stroke bike engine. No background noise it just sits at random numbers. Waste of time.

★★☆☆☆ Tried to use this for a single cylinder 2 stroke scooter motor. It told me that the engine was idling around 7k rpm with low ambient noise.

★★☆☆☆ Its saying my MB O 305 engine witch redlines at 2200rpm also idles at 2200rpm. Is seems correct at the top, but not at all at idle. Might be that it idles under the 500rpm the app has at minimum...