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Tach from EI and Mag?

vmirv8bldr

Well Known Member
I have a Lightspped EI and a single mag setup, and am using a GRT EIS4000 for engine monitoring. Is it possible to get RPM from BOTH sources so that in the event one fails, or is switched off for any reason (runup) you can still see RPMs?

Thanks,
Bart
 
I have the same setup

I just tolerate the 10 seconds that I don't have a rpm reading at run-up.

You're not going to take off with an electrical failure with half of the ignition system if the EI is out.

And

If it quit in flight and you had to find home on the ground with the mag only, I doubt knowing the exact rpm would be much of an issue.
 
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Yes.

I have a Lightspped EI and a single mag setup, and am using a GRT EIS4000 for engine monitoring. Is it possible to get RPM from BOTH sources so that in the event one fails, or is switched off for any reason (runup) you can still see RPMs?

Thanks,
Bart

There is an update to the EIS that you can purchase that among other things handles two ignition systems.

I did it and it worked as advertised using a mag and a P-mag (EI).

Call Sandy at GRT and she will make it happen.

James
 
You can also wire a switch to change tach inputs. I usually leave it set to the mag input, because the RPM drop when turning off the mag is minimal. The Lightspeed produces twice as many pulses, which requires dividing by 2 to get the correct RPM number in my setup (I would only have to do this if the mag failed).
 
Electronics International Inc. offers a tach "R-1-4LM"

Utilizes both the EI square wave and a mag. It will show you mag drop, as well as an "outage" of either ignition source. FWIW.

Best to you,

Matt
 
Latest EIS can do both

I got a note from Sandy indicating the latest version of the EIS can accommodate dual Tach inputs from different type sources. So you would not have to divide by two when switching from reading the LS vs Mag.

Bart
 
James,
Can you post what your EIS settings you are using to make this work with the new modification? ie High/Low Pulses per Rev 1/2.... etc.
 
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There is an update to the EIS that you can purchase that among other things handles two ignition systems.

I did it and it worked as advertised using a mag and a P-mag (EI).

Call Sandy at GRT and she will make it happen.

James
I have the same issue with my EIS. I talked with Sandy the week before Oshkosh. She told me about this upgrade. It cost $100. You ship your unit back to them, they make the upgrade and ship your unit back. She said there is a quick turn around. However, because of Oshkosh they will not be back into the shop until August 9th.

Allen mentions putting a switch to change the tach input. This would not work on the EIS 4000 unless you changed the pulse input setting for the tach each time you switched from EI to mag as they require different pulse inputs.
 
Allen mentions putting a switch to change the tach input. This would not work on the EIS 4000 unless you changed the pulse input setting for the tach each time you switched from EI to mag as they require different pulse inputs.

Actually it works fine, but with the pulse input set for a mag the EI setting on the switch causes the RPM to read too high by a factor of 2. Its not difficult to do the division. The switch really is just there to provide backup if the mag fails to provide a good signal. I generally don't use it to check RPM drop, because the drop with the mag switched off is much smaller than with EI switched off.

The upgrade to two-channel tach is definitely a better option if you're starting from scratch and don't mind spending a bit more (this wasn't available when I did mine).
 
MVP 50

Mathew Sharp,
how can this be set up with an MVP-50?
IO-540 1Mag and Lightspeed ignition?
 
James,
Can you post what your EIS settings you are using to make this work with the new modification? ie High/Low Pulses per Rev 1/2.... etc.

I would if I had them handy.
The plane is in another state. :)

I am sure that they were either in the directions or that Sandy told me over the phone.

I recall it being a non-issue after talking to her.

James
 
Tach Gen too

There is also the encoder that goes into the tach drive that Vans sells but getting the drive cable length right and mounting the sender can be a hassle. Also, the instructions that Rocky Mountain Instruments sends on their version of the EIS shows using two capacitors to a common signal line to their device instead of the toggle. I don't know how that would work with electronic ignition. but considering the different number of pulses mentioned earlier in the thread that would probably not be a good solution.

I'd probably get my EIS upgraded but $100 seems too steep. Does anyone on VAF know if it is software only or hardware change too?
 
Does anyone on VAF know if it is software only or hardware change too?

Its a hardware change too that requires you to send your EIS to Grand Rapids. I have done that, but now cant seem to get the settings right in the box. If anyone has broken that code please post... (One slick, one Lightspeed Plasma II)
 
Its a hardware change too that requires you to send your EIS to Grand Rapids. I have done that, but now cant seem to get the settings right in the box. If anyone has broken that code please post... (One slick, one Lightspeed Plasma II)
anyone have their EIS settings for this?
 
I am looking for the settings for the EIS 4000 Grand Rapids for dual tach inputs -- one slick mag, one Lightspeed II.
 
EIS 4000 settings

Settings are Tach P/R = 1 for the mag with mag pulse wire connected to EIS yellow wire on pin #12( use the resistor per manual 27k ohm).
The Electronic ignition is connected to pin 24 yellow/grey wire. Set that code to 2 and I believe it is on the set up as either N1 or N2 I can not remember // correction// the current version has a field in set up for "Tach2P/R". The display screens use a field name "Tach" which will display RPM from Tach1 if available and in it's absence will display Tach2. If you want to display Tach2 rpm specifically use field name "N2" in a user definable page. You may need to set sensitivity to high for the Lightspeed, especially if you cheated and did not use a shielded wire as Klaus calls for. I used the shielded wire and my tach2 input reads OK on low sensitivity.
 
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