Design Principles

On this page we’ll provide a bit more detail on various design and operational topics.  Selections will reflect the frequency of customer questions or current topics from the industry at large.

Future Proofing

If you follow trends in electric vehicles, you might have noticed Tesla’s new Cybertruck and the long list of featured innovations.   Regardless of whether you love or hate the truck’s appearance, it includes several revolutionary new technologies.  One is a new 48-volt bus architecture Tesla credits for a substantial wire related weight savings – a feature all the more important for aircraft.  To realize the full benefits other components will need to be converted, but it’s worth noting E-MAG ignitions have been 48-volt compatible since May of 2021.   This is a behind-the-scenes feature that customers have never asked about . . . . .  but we did it anyway.

High Energy Spark – When is enough… enough?

Ignition shoppers are sometimes encouraged (by our competitors) to compare the spark energy output of different electronic systems.   The implication and challenge being,  the greater the energy – the better the ignition.  E-MAG has a distinctly different perspective that runs counter to some, if not most, in the industry.   To explain, we’ll start with our own design objectives:   Spark energy should be increased ONLY to the extent necessary to achieve the intended result – AND NO MORE.

This approach stems from a simple truth.  The benefits of high energy spark are non-linear.  Meaning, after an initial boost there is little or no benefit derived from more (and more) energy.  There is, however, an increased burden in the form of additional heat, stress, wear, and weight associated with the creation and constraint of excess spark energy.  These can be managed, but if the additional energy doesn’t produce a benefit – why do it in the first place?

E-MAG uses a closed-loop control to manage and regulate spark energy at predetermined (elevated) levels.   Our energy output is a function of deliberate design choice – not a limitation of capacity.   Again, the goal is to deploy the minimum energy required – not the maximum amount possible.

This energy strategy has other benefits.  E-MAGs are smaller, lighter, and operate cooler than competitors.  This allows us to mount directly on the engine . . . . where ignitions were designed to go.  Even more important, direct mount provides the drive for E-MAGs built-in electrical power back-up . . .  which is the “elephant in the room” when it comes to comparing and contrasting the merits of flight-critical electronic systems.   

One vs. Two Electronic Ignitions?

Customers who start with one E-MAG, and later add a second, typically report a 70%-30% progression in terms of performance gains.  70% of the benefits for half the investment is a great bargain.  But the remaining 30% is still significant.

Because E-MAGs have built-in electrical power, operators are free to convert one at a time or both at once – without the added task of providing external power supplements.   But in all cases, the goal is to end up with matched plug firing (i.e. matched ignitions).  This will be impossible if you keep one magneto.

There are two reasons for running a split system (one magneto and one EI).

  1. As the first step in your transition to a dual EI – one now and one later.  This is a common and reasonable route.
  2. As a work-around for an EI that does not have an attractive or practical electrical power plan.  If the electrical bus goes off-line for any reason (taking the EI with it) the magneto can get you down.

We need to be clear.  In a split-system, keeping the magneto does not hurt anything.  That’s not the issue.   The problem is it doesn’t “help” anything.  Operating alongside an EI, the magneto is most often firing 1) weak and 2) late.  It’s essentially turned into a seven pound oil plug.  In a small aircraft, where builders work hard to shave ounce everywhere they can, this is unacceptable and unnecessary.


External ignition control devices for your (4-cylinder) E-MAGs.  Do you need one? [spoiler alert – likely no]

Series 113 and 114 ignitions have a (serial) com port connection thru terminals #2 and #3 of the control plug.   However, these terminals are most often not used in this capacity.  Instead, they are used as a handy short-cut for configuring the ignition timing advance range.  Control plugs come from the factory with a short jumper wire between #2 and #3 as most short-cut setups use the jumper.

Control plug terminals #2 and #3 can be used as either:

  1. A simple means of shifting the ignition firing range, (Jumper IN or Jumper OUT along with TC-Offset), so ignition timing is compatible your engine – see current manual (Downloads page).
  2. Or they can provide a serial interface (Series 113 and 114 only) for external devices that monitor and/or alter internal ignition configurations – Advance Shift, Max Advance, Max RPM, Tach PPR, and more.   Note: Third party devices are sold, supported, and serviced by their respective manufacturers.  E-MAG will be happy to assist, but does not provide direct support for these devices.

Fine-tuning your ignition timing, if needed at all, can be done with either method.  The Jumper/TC-Offset method is simple, built-in, and free.  If you subscribe to the philosophy of keeping things simple, you’re ready to go.  If you need/want a more intimate interaction, and don’t mind another wonder-box in your dash, third-party devices can provide some very cool interactive features.  But if the question is do you “need” one, our answer is typically no.  If you choose to use a remote device, please be careful.  Changes to ignition timing should be done cautiously and thoughtfully.  You have the keys to the kingdom.