What does it weigh?

SIM4P - 4.4 lbs. SIM4N - 4.0 lbs. SIM6C - 5.0 lbs. SIM6L - 5.2 lbs.

How is the SIM turned on and off?

The SIM is turned on and off with the existing ignition switch through the p-lead wire connected to the p-lead terminal of the SIM.

Why is variable timing not available for a turbocharged, turbo-normalized or supercharged engine?

Upon loss of manifold pressure input, a SIM configured for variable timing will calculate advance based upon pressure altitude. In this unlikely scenario, variable timing may result in engine detonation margins too narrow to safely operate a turbocharged aircraft at high altitudes.

Can I use a Bendix harness?

No. The SIM only interfaces with a Slick magneto harness. If you are replacing a Bendix magneto, you will also have to replace the Bendix harness with a Slick harness.

Can I use automotive spark plugs with a SIM?

The SIM is compatible with all automotive and aviation spark plugs. SureFly’s FAA STC’s do not grant permission to use automotive spark plugs in FAA certified engines. You may only use spark plugs FAA-approved for your application.

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).

Will the SIM help my engine start?

Absolutely! Compared to a magneto, the SIM provides a more accurately retarded spark and a more consistent, higher energy spark at low engine RPM. Hot-starts are greatly aided by the installation of a SIM, but keep in mind SureFly can’t remedy fuel system shortcomings!

Should I replace the impulse or non-impulse magneto with a SIM?

SureFly recommends replacing the impulse coupled magneto. This is to reduce the possibility of impulse coupler mechanical failure and also to help the engine start better.

Can I replace both magnetos with SIM’s?

No. At this stage SureFly’s FAA STC only accommodates the replacement of one magneto with a SIM. SureFly intends to certify the replacement of the second magneto in the near-future.

Does SureFly have a SIM replacement for a dual magneto?

Unfortunately not.

Will the SIM work with Electronics International brand tachometer?

Yes, it is necessary to replace the existing isolator with an inline resistor. Different p-lead wire gages, lengths and ignition switches will require different resitances for the EI tachometer to read the SureFly's p-lead signal. In our experience, most installations require anything from an 8K to an 18K resistor.

Will the SIM work with Horizon or B&D Industries brand tachometer?

Not at this time, it’s in the works, stay tuned.

What are the advantages of a SIM configured for fixed timing over a magneto?

Solid-state magneto with the benefit of improved reliability and zero maintenance (no rebuilds & no overhauls) over the lifetime of the SIM.

What is the service life of a SIM?

Return the SIM to SureFly for evaluation after 2400 hours of SIM operation.

Why is variable timing not available for engines that burn less than 100LL fuel?

We have a limitation on our STC because we have only tested the variable timing schedule with 100LL fuel.

What spark energy and voltage does a SureFly output?

We are often asked about how "hot" our spark is. What most people actually mean when they use that term is - "How many volts will your ignition output?" The truth is, voltage is only half of the equation. The total output energy is measured in millijoules(mJ), and the voltage at the spark plug varies in proportion to the gap of the spark plug. The SIM produces 27mJ of energy at the spark plug (the same as a Slick Mag at 2700 RPM) and 60mJ of energy during start sequence.


What is the recommended spark plug gap for the SIM?

SureFly recommends following the spark plug manufacturer's recommendations for plug gap.

Where do I connect the SIM to aircraft electrical power?

​SureFly requires you to connect the SIM directly to the aircraft’s primary battery. You may connect the SIM power wire directly to the battery’s positive terminal or to the battery input terminal of the master solenoid. A power wire harness with terminals is provided with the SIM.

Can I protect the power wire with a breaker instead of a fuse?

No. SureFly requires you to use an inline 10A slow-blow fuse to protect the power wire. An inline fuse holder and fuse is included with the SIM.

Where is the best place to connect the SIM to manifold pressure?

A 36” long 1/8”IDx1/4”OD hose is provided with the SIM to connect manifold pressure. The installing mechanic is required to provide appropriate fittings based on the choices below: Option (a): Tap into existing MAP gauge plumbing with a T-fitting (recommended). Option (b): Hose barb in threaded port on cylinder head. Option (c): Hose barb in threaded port along intake track.

Post Installation

What RPM drop should I expect during a Mag check at run up?

You should expect a normal 50-100 RPM drop during a mag check. If the rpm drop is greater on the SureFly, you should verify the remaining magneto is timed correctly - it is not uncommon for the remaining magneto timing to have changed a few degrees from its initial installation.

Why does the engine stumble during mag check?

On some aircraft there is a slight engine stumble when doing a mag check. We have discovered that some mag switches actually ground both ignition systems in the transition between Left and Right positions. The SureFly Ignition Module requires a few milliseconds to power up after being tuned on. This only occurs on a small percentage of aircraft. If you are one of the lucky ones, stay tuned as we are working on a solution. Please make sure your ACS aircraft ignition switch is in compliance with AD 93-05-06.

Can I perform a high voltage lead test?

Do not preform a high tension lead test with the harness connected to a SureFly.






Tel: 817-373-5161

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