Surefly RPM Problem

[jchang10]

Surefly setup on Skyview EMS P-lead connection

Has anyone installed a Surefly EI in their aircraft? There appears to be a RPM issue with other EMS systems , I am attempting to determine if there is any issues with using the standard wire currently used for the Magneto with the resistor attached, before i start taking things apart to find out...

forum.flydynon.com

Anybody else installed Surefly yet? I did a drop-in replacement. Unfortunately, when checking the mag drop on Surefly, the RPM reading goes to ZERO. That is unfortunate.

I am connected as the Dynon Install manual recommends under the section P-lead pickoff (Lycoming and Continental) pg 7-47. Uses two 30k ohm resistors.

https://www.surefly.aero/faq According to their FAQ, the p-lead sense line might be an issue.

Does the SIM output a tachometer signal?

The SIM outputs a 60Vdc spike with a 10Vdc offset on the p-lead (2 pulses per rev for 4 cylinder models & 1.5 pulses per rev for 6 cylinder models).

Hoping for any suggestions!

Jae

 

[Raymo]

Resistors are only required for magnetos. Not need for electronic ignition (per the install manual). You mentioned PMag, which is a different EI product. It also does not use a resistor for RPM/Tach.

 

[jchang10]

I meant p-lead sense line not p-mag. This is for the Surefly EI mag. www.surefly.aero.

LYCOMING EIS

www.lycoming.com

I believe the Lycoming box is the same from Surefly.

 

[Raymo]

I believe you are correct on the Lycoming/Surefly thing.

Remove the resistors and I think you'll be set.

 

[DBRV10]

And just for the record.......Mag drop in RPM is not the best method, although that was what we were all taught. Its origins are from the dark ages where no EMS existed.

You should do your mag checks in flight at TOD. But if you want to do one on the ground, 1500-1700 RPM (no more) and so lean that you had to add mixture to make it reach those speeds smoothly. Then on each mag, you are looking for all 4/6 EGT bars to rise and not be flakey. Full rich works but is way less diagnostic, it will mask faults. Doing high power in flight mag checks will help you find faults well before they appear in a traditional ground check, and that is desirable wouldn't you say?

Hope that helps, as a side note to the original question.

 

[XPRSAV8R]

I have dual SureFly units. Did you receive a "tach board" from SureFly (contact Jason)? You will wire your unit(s) to the tach board (~8 cm x ~15 cm) which takes signals from the unit(s) and converts it to .5v square wave output for your tach input. I use the SV-EMS-220 that converts the pulses into meaningful RPM measurements. I can't recall the pulse to RPM ration off-hand, but this works perfectly for me.

 

[jchang10]

@XPRSAV8R Hmm, this is the first I heard of a tach board. Interesting. I will have to contact them about it, then.

 

[jchang10]

I finally tried going from the 27k resistor to a 4.7k resistor (zero rpm) and to no resistor (zero rpm). It does not look like anything with the resistors will work. Might be the 10v bias voltage. If that is the case, then having a capacitor to filter the bias voltage may work?

Would be nice to get confirmation from Dynon. This might be a common question as EI's become more popular.

 

[djones]

I have dual SureFly units. Did you receive a "tach board" from SureFly (contact Jason)? You will wire your unit(s) to the tach board (~8 cm x ~15 cm) which takes signals from the unit(s) and converts it to .5v square wave output for your tach input. I use the SV-EMS-220 that converts the pulses into meaningful RPM measurements. I can't recall the pulse to RPM ration off-hand, but this works perfectly for me.
View attachment 3739

Did a little research and this is the correct answer. The PLeads won't work as a tach signal for SkyView. You will need to get the "Tach Board" from SureFly. We should have no problem using the 0 - 5 volt square wave from the board on our low voltage
RPM inputs on Pins 34 & 35

 

[Paul Brooks]

I have a dual Surefly EIS installation in an Acrosport 2 IO-360 200 HP with Dynon touch very easy installation. I called Surefly in texas and had the Tach2 board made in 1 day and received the unit in London Ontario Canada 3 days later. Great service and worth the $160. Well built unit and very easy to install with no issues.

 

[Walt]

Did a little research and this is the correct answer. The PLeads won't work as a tach signal for SkyView. You will need to get the "Tach Board" from SureFly. We should have no problem using the 0 - 5 volt square wave from the board on our low voltage
RPM inputs on Pins 34 & 35

This was recently posted at Van's Air Force forum regarding this subject:

"I installed a Surefly with my Dynon SKyview Classic. I connected the original Slick mag P-lead to the Surefly and did not change the original Dynon resister or wiring.

The tach signal from the Surefly to the Dynon Skyview works perfectly on either the Surefly or the P-mag.

I did buy the Surefly "tach box", which I did not use."

CONFUSING!

​

 

[XPRSAV8R]

This was recently posted at Van's Air Force forum regarding this subject:

"I installed a Surefly with my Dynon SKyview Classic. I connected the original Slick mag P-lead to the Surefly and did not change the original Dynon resister or wiring.

The tach signal from the Surefly to the Dynon Skyview works perfectly on either the Surefly or the P-mag.

I did buy the Surefly "tach box", which I did not use."

CONFUSING!

​

I don't know about P-mag's, but I do know the SureFly units well. I was one of their first dual customers back in 2017. After months of troubleshooting, I called SureFly and was advised by Jason of SureFly that it was not possible without the tach board. Their units produce pulse waves and must be converted to square waves for Dynon's tach. I suppose anything's possible, but my installation has been bulletproof for 2 years now. I can only recommend that you speak to Jason or an engineer there.

 

[Walt]

Roger that....definitely will do. Thanks