You say you want a (pulse per) revolution

[LettersFromFlyoverCountry]

Can anyone confirm that with a two-blade prop, the pulse per revolution for a Lightspeed EI (Plasma II) is 2 and for Slick mag it is 1?

[Mike S]

I dont think the number of prop blades have anything to do with it, unless you are using an optical tach.

The magneto does run at half engine speed, and for a Light speed with the front mounted sensor, it is reading actual engine speed. The light speed unit that has a sensor in the mag spot----dunno if they have a circuit to run at engine speed, or at mag drive speed.

Love the new tag line, "Plane done, Money gone"

And, Congrats on the "Plane Done" part

[LettersFromFlyoverCountry]

C'mon people! Pretty sure I'm not the first guy with one mag, one lightspeed and a GRT 4000 SIS.

[Sparky]

Bob, You are correct (for a 4 cylinder engine). It doesn't matter how many blades the prop has.

Assuming you are using a magnetic tach sensor on the magneto, you only need to use the magneto sensor. You don't need, and probably wouldn't want both connected. The magneto sensor will provide output pulses as long as the engine is turning regardless of whether the magneto is "on" or not. The EI will only provide output if the electronic ignition is on. You only need to connect both if you have dual electronic ignition.

[Lars]

Originally Posted by LettersFromFlyoverCountry

C'mon people! Pretty sure I'm not the first guy with one mag, one lightspeed and a GRT 4000 SIS.

Option "2" as described on page 22 of the EIS rev K manual. Which happens to correspond to one pulse per revolution.

Oh yeah, you should be able to connect both your mag and your LSE ignition to the EIS. The EIS will read either or both, so you will always have a tach display even if the LSE drops off line.

[N427EF]

While I can't remember seeing a reference specifically describing the output pulse from LightSpeed's EI, I can assume that it is one per revolution.
As to hooking up only the magneto that would be up to you.
You will not see an RPM indication for your runup magneto check if you only hook up the mag.

[Sparky]

In my above reply I assumed you are using a magnetic tach sensor on the Slick magneto, Like this:



This sensor will output a tach signal of 1 pulse per crankshaft revolution on a 4 cylinder engine regardless of whether or not the magneto is on.

If you are taking the magneto tach signal from the P-lead, then you would want to connect both the magneto and EI tach signals to the EIS.

[jrs14855]

From the Lightspeed article in Sport Aviation " the Lightspeed system is a wasted spark system"-it fires twice as often as a mag, the second spark occurring on the exhaust stroke does nothing.

[Sparky]

On the drawing for the input connector Pin 6 (tach output) it specifically states, "2 PULSES/REV (4 CYL)".

[LettersFromFlyoverCountry]

Originally Posted by Sparky

If you are taking the magneto tach signal from the P-lead, then you would want to connect both the magneto and EI tach signals to the EIS.

Yes, that's what I'm doing.