swisseagle

swisseagle

Well Known Member
Hello

I have a dual PMAG setup on my IO-320 / RV-7A. It is time to route the ignition wires now, but then, a important question pop up:

How to layout the ignition system?

Version 1: L = 4x top / R = 4x bottom
The left PMAG ignite the top plugs.
The right PMAG ignite the bottom plugs.

Version 2: L = 2x L-bottom;2x R-top / R = 2x L-top;2x R-bottom
The left PMAG ignite two bottom plugs on the left an two top plugs on the right.
The right PMAG ignite two top plugs on the left and two bottom plugs on the right.

Version 1 will give more drop difference during a run up check.
Version 1 will look "cleaner and easyer on paper (in my mind too ;) )

Version 2 will have a more "symetricaly" drop in a run up check.
Due to this, Version 2 will be more easy to detect a failure/bad plug/bad nozzle.

I think both versions would be ok, but:

Which version is better? Which version should I build?

I will also contact Brad at EMAG-Air with this.

Thanks for any input!
 
Last edited:
Hi Dominic,

For what it's worth I did version 2 when I installed my P-Mags, mag checks are pretty even.

Cheers
 
I use dual P-Mags with the EIC. I use version 1. Left top - Right bottom. If there's a plug / wire problem it's much easier to find - top or bottom. If one P-Mag fails, the burn will be the same in all 4 cylinders. The timing for the top is the same and the timing for the bottom is the same. You will never get the 2 P-mags timing exactly the same, one will always be advanced to the other.
 
I did version II, same as if you installed standard mags.

Just make sure to ground each P-mag independently to local case bolts. DO NOT ground them to the forest of tabs on your firewall! I cannot stress this enough. We have found with the EICommander that when a customer calls in with an issue regarding false timing divergence alarms it is usually because of how they are grounded. The issue may have more to do with the EIC than the P-mags but we are not sure. What we do know is that when the P-mags are installed per the Emag manual, the problem goes away.
 
From E-MAG

Brad answer:

Hi Dominik:

You can assign cylinders either way. If you route with the traditional criss cross method (2up/2 down) you will have a more balanced installation, which is only significant in terms of preserving a balanced L/R drop at run-up. Even balance is more important for traditional magnetos (more mechanical wear and tear parts) than it is for electronic ignitions. You can choose either method. If you rout 4up/4down you might introduce a run-up bias for one side or the other. But in your personal plane, you can quickly identify a normal baseline for your particular installation.

I hope that helps.

Brad Dement
E-MAG Ignitions
2014 Greg Street, Suite 112
Azle, TX 76020
 
We routed 4 up, 4 down because we originally installed auto plugs top, aviation plugs bottom.

These have now been swapped to auto plugs top and bottom.

There was an immediate improvement in running and cylinder temps, but as we had to re time everything at the same time, it can't be ruled out that we were running advanced.

The 8 has an EIC so we will be able to tell.
 
How much RPM drop in this configuration?

Thanks for all your reply's!

I can do both versions, both will work, so I still have to choose.

How big is the RPM drop when I go for this version?

Version 1: L = 4x top / R = 4x bottom
The left PMAG ignite the top plugs.
The right PMAG ignite the bottom plugs.

A testcell engineer for car-motors told me: the cylinder is symetrical, so there would be less differences in combusion when both mag's not firing at the absolute same time. This for Version 1.
 
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