Make your iPhone a strobe tachometer

Engine troubles? Try here.
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Make your iPhone a strobe tachometer

Post by pinzinator » Wed Oct 21, 2020 12:39 pm

If you have an iPhone, go to the App Store and search for Strobe Tachometer. Download the basic version, 'Productivity'. This app turns your phone flashlight into a strobe light, based on the RPM you are trying to coordinate with. Once you select the correct RPM, the device you are measuring will seem stationary, like it is not moving. Remember the old direct drive turntables and how you set the 33 1/3 speed by rotating a knob until the dots stopped moving? Same principle. You can try it on a standard electric fan first to practice.
With PinzSSI the standard dwell/tach will not work. I wanted to calibrate my tachometer, but first I had to know the actual RPM to compare with. Using my phone, I was able to determine that my engine idle was exactly 500 RPM.
I used yellow chalk to outline the 2 openings in the crank pulley to make visibility better.
I didn't check the engine fan RPM at idle, I might as well check it out for shits-and-giggles! This would be a good way to determine the pulley ratio.
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With the engine running, push the + and - buttons until you get to the point to where the pulley is stationary, like using a timing light. I figured the engine speed to be between 450 and 600, to I started at 450 and hit + until the strobe light and pulley matched up. From there I when up and down 40 RPM each direction to verify.
IMG_0147.JPG (885.53 KiB) Viewed 231 times

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Re: Make your iPhone a strobe tachometer

Post by rmel » Thu Oct 22, 2020 9:49 am

Nice find Rick !!

Makes a good tool for calibrating an eTach as well.
Puller: 71' 710K 2.7L EFI aka Mozo
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Re: Make your iPhone a strobe tachometer

Post by Joeri » Thu Oct 22, 2020 11:03 am

500 Rpm is a bit low for a pinz...they are normaly around 850 Rpm ' s :wink:

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