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RPM issue advice

cropdusterdave

Well Known Member
Newly minted RV-7. Setup is Lycoming O-320 160 HP with a Sterba wood combination prop and Dynon skyview. Full power static run-up us only showing 1650 rpm. Pulled back a bit in cruise 1400 indicated gives me a decent cruise speed (140 MPH) and 7.5-8 GPH burn. Wide open in cruise maxes a little less than 2,000 RPM. Knowing that most folks will cruise around 2200 RPM makes me aware that I am at least displaying low RPM. Audibly...the engine sounds like any other O-320 I've flown behind. I'm wondering if I may have a sensor issue. Another clue....when I kill the rt mag on the run-up, the indicated rpm drops from 1600 all the way down to 600. It's definitely not dropping that far, however. It sounds and behaves the same as when I kill the other mag for a 200ish rpm drop. I hired out the wiring...so I'm not savvy on the intricate details on that. Any ideas or tips would be greatly appreciated!
 
Borrow a prop rpm measuring tool from your nearest model aircraft club and use it for a quick check of your tachometer.

They are light sensitive and just measure the blades going by in a safe, non-contact method.
 
EFIS config issue? No way you're that fast at that rpm.

I agree. And the excessive mag drop indication on the left mag tells me that something is up there. However, having not wired the thing...I'm in the dark. I'm following up with the avon shop.... Thought someone here may have seen the same situation.
 
Check the RPM configuration in the Dynon. I believe you should be set to 2 pulses per revolution.

Set Pulses / Revolution (PPR): SETUP MENU > HARDWARE CALIBRATION > EMS CALIBRATION > TACHOMETER CALIBRATION
 
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