Surefly Sim4P 4 Cylinder Impulse Coupled Magneto Replacement

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Part# 08-17074
MFR Model# SIM4P


Now approved for many turbocharged twins and most 4- and 6-cylinder Continental & Lycoming powered aircraft.

Note: Surefly strongly recommends the customer purchase a NEW slick-style harness and fresh spark plug set with every SureFly SIM.

The vast majority of 4-Cylinder applications will replace the impulse coupled magneto. 4.4 lbs.

SureFly is an FAA certified electronic (solid state) magneto replacement. The SureFly Ignition Module replaces one magneto - generally the left or impulse-coupled/starting magneto on most aircraft. 4 and 6-Cylinder models are available for Lycoming and Continental engines.

Replacing just one magneto eliminates magneto maintenance and cuts associated costs in half! Zero maintenance. Zero rebuilds. Zero overhauls. Most fixed-wing single engine aircraft can enable SureFly's advanced timing feature for improved cruise flight efficiency. Many other aircraft will be able to use the advanced timing feature as the FAA extends SureFly's Airframe STC AML.
California Prop 65 Warning Symbol

WARNING: The product may contain and/or expose you to a chemical(s) or substance(s) which are known to the State of California to cause cancer and/or birth defects or other reproductive harm.


For SureFly customers, 500 hours is simply not good enough. SureFly Ignition Modules provide operators a 2,400 hour operating service time. No inspections, no rebuilds, no overhauls. That prevents scheduling headaches and down time. That saves money. Period.

SureFly Ignition Modules have no mechanical parts that wear and all solid-state electronics. There's no need to disassemble a SIM like a magneto every 500 hours - which eliminates the chance of introducing a maintenance related failure.

SureFly Ignition Modules deliver a more consistent spark energy with higher accuracy than traditional magnetos. Variable timing advance provides SureFly customers real fuel savings. Low power consumption and light weight (up to 2 lbs. lighter than a Bendix magneto) make SureFly Ignition Modules light on fuel and light on the wallet too.

Better Starts
SureFly perfectly controls timing at TDC below 400 rpm which combined with longer spark dwell and the option to use wider gapped spark plugs, makes starting a breeze, greatly minimizing wear and tear on high performance starters and electrical systems.

SureFly Ignition Modules are hand built in Granbury, Texas almost entirely from components manufactured in Texas and Michigan. Designed, engineered, created and supported by the same team that brought you Sky-Tec starters and Plane-Power alternators, our approach to SureFly shares the same commitment, experience and passion for creating and bringing sensible, affordable solutions to the piston engine aviation market.

With the low cost of the units, combined with SureFly's potential fuel savings and low maintenance/replacement costs, there is simply no better value in magneto replacements for Lycoming and Continental engines.


  • Aviation spark plugs – gapped .016 to .036
  • Slick style harness – Shielded aviation harness
  • Input voltage 6-30 volts
  • Avg. Current @2700 500mA
  • Retards spark to TDC for starts
  • Up to 38 degrees Ignition advance – RPM & MP based
  • Hall Effect sensors provide velocity and position input
  • Manifold pressure sensor range – 6-74 inHg
  • Operational temp range -35 to 250 F
  • Minimum MTBF 2000 hrs
  • No interval inspections
  • RPM range 0-3500
  • Voltage to bridge .036 spark plug gap
  • Minimum 35mJ spark energy
  • 50mJ nominal energy


    Intelligent Timing Advance
  • For non-turbocharged engines, SureFly controls spark advance up to 38º before TDC as determined by manifold pressure and RPM (engine power setting). Each engine's base timing advance is read off the data plate and set into the SureFly Ignition Module or, "SIM" at installation. The timing advance schedule is hard set at the factory, when the SIM is manufactured, to provide the highest possible combustion efficiency.
    No Mechanical Points
  • Not only are points and condensers a point of failure in magneto ignitions, so are rotors and caps as they carbon track and provide alternate paths to ground as resistance builds in the system. That's why SureFly utilizes none of these antiquated technologies. SureFly components are all solid state and industrial-grade electronics.

    The result is zero maintenance, zero overhauls, no rebuilds, and no maintenance costs whatsoever! Nothing to wear. Nothing to maintain. Run it to 2,400 hours of SIM operation.


View the latest eligibility chart at Application Guide

If any of the following items apply to your installation, please call SureFly at 817-373-5161 before proceeding with the purchase or installation of a SureFly Ignition Module:
  1. Your aircraft tachometer is one of the following:
    1. Horizon,
    2. Electronics International,
    3. EFIS or Engine Monitor that requires magneto P lead inputs,
    4. EFIS or Engine Monitor that requires a 0-5 volt square wave input,
  2. Your aircraft has more than one engine,
  3. Your aircraft has an existing electronic ignition,
  4. Your aircraft has one of the following STC’s:
    1. Western Skyways Turbo STC,
    2. Auto Fuel STC.
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Installed on O-200 engine. runs smoother, climbs better and there is about 50 rpm gain at full power. K. Petrov

Konstantin P Verified Purchase


May 21, 2022

Impressed with the completeness of the kit. Everything needed for a straight swap from the old magneto is in the box, including screws, washers, 20g wire, crimp terminals, placards etc. Even more impressed with the performance of the Surefly ignition. Cold or hot, my 0-320 now starts like a car. Subjectively, it seems smoother with a little more power, even on the fixed timing setting. Looking forward to using the variable timing option in due course. Very happy.

Malcolm K Verified Purchase


April 26, 2022

Been having problems staring the plane. The new magneto works perfectly and plane starts easily.

Richard D Verified Purchase


March 22, 2022

We are phasing in these units in our club airplanes and are exceptionally impressed with them. All units so far are Impulse Coupled units. Starts are great and we are seeing notable fuel consumption reductions.

Pugetsoundflyers, I Verified Purchase


March 9, 2022

Magneto was very easy to time and install. No time yet to run engine.

James R Verified Purchase


February 12, 2022

Mike Z Verified Purchase


January 18, 2022

Finally, a system that gives modern reliability to older engines. Swapped out my left coupled on my 65 Cherokee and the performance increase is very noticeable. Can not say enough good about how easy the install was or how well it runs. Also, it starts before the prop even makes one full rotation. I will not have another plane with a Surefly on it

Clifford M Verified Purchase


January 1, 2022

This is the second Surefly Mag that I have installed. The first went on my own 150 and I used fixed timing. The second went on a PA28-180 and was set up for variable timing. In both cases the installation was straight forward. The engines, especially the PA28, start up quickly and run smoother than before the change. I can not attest to fuel savings for the variable timing install because we have not flown the plane much. The mag on the 150 has been on for a few hundred gourds without a problem. We are very happy with the improvement in engine performance, smoothness and quick starts. I can not think of a good reason not to switch one mag to electronic.

Chris G Verified Purchase


December 27, 2021

My I A had issues with this I might have gotten a defective part we have another one on the way so hopefully it’ll work I’m excited to see if it’ll make my io360 perform even better than it already does

William D Verified Purchase


December 21, 2021

Fitted the SureFly after having a Magneto issue ! Early days yet but starts easier and runs smoother.

Mark F Verified Purchase


October 14, 2021


Please note, Pilotshop's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Pilotshop assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Mooney utilizes the shower of sparks system and does not have an impulse coupler. Would I buy the Sim4p or the Sim4N?

A Shower of Sparks system would be replaced by a SIM4N. As a side note, that is a Bendix magneto and will require the installer to change the spark plug harness with one that mates to a Slick magneto. All SureFly units mate with Slick style harnesses.

Q: Regarding the Surefly: Do you need to change spark plugs or still use the aviation ones? How do you save fuel with this?

Per Surefly: With any of the SureFly units we recommend the owner stay with whatever plugs are approved for that aircraft. They work just fine with auto plugs in the experimental world, so the unit itself doesn't care. Fuel savings are dependent on the aircraft and the operator. Lots of variables there. In general, we might expect some savings when running lean of peak at cruise. The biggest advantages are NO MAINTENANCE and easier starting.

Q: So I do have a Horizon electronic tach which I really like as it shows the performance of both mags. So if I use this to replace one Mag , how will it interface with my Horizon tachometer? Thanks

At this time, the Horizon tach is not supported with SureFly. It is in the works, stay tuned.

Q: Is there a Horizon tach fix yet?

At this time, the Horizon tach is not supported with SureFly. It is in the works, stay tuned.

Q: Do you have to replace both magnetos on Lycoming engines when installing a SureFly SIMP4P?

No, you do not.

Q: Can you replace both mags with the sureflys?

Per surefly: On an experimental, yes. However, you have to have a back up battery system. If you wish to proceed with dual mag replacement, please contact Surefly tech support to be sure installation is done correctly. If the aircraft is certified, you can only install one mag.

Q: Is everything shown in the Hardware Kit drawing included with the Surefly SIM4P unit?

Looking at the Hardware Kit drawing: Everything that is a dotted outline is not included. The remainder of the items listed are either already on the SIM4P or in the installation bag that comes with the SIM4P.

Q: What slick harness would I need to order? I would be replacing my bendix mag with the surefly.

This will depend on your engine make and model, spark plug barrel size, and if you are replacing the left or right mag. With this info, use the slick by champion application chart to select the harness needed for that application.

Q: slick makes different harnesses for my engine based on the model of the magneto. telling me to use their chart does not help. what model slick magneto does surefly copy?

When using the Slick by Champion Harness application chart, you will need to first select 5/8 or 3/4 barrel, then find your engine, Slick mag model, then left or right harness. Example: 5/8" barrel plugs, Lyc O-360-A1A, narrow deck. The first three columns of the mag models are for Slick, and this application has an "X" for the M4006 harness kit, left is M2983 and right is M2984. If you replaced your right mag you would want the M2984 harness, or if you did the left, you would want the M2983, or if you replaced both then order the kit M4006.

Q: Lycoming in the process of releasing engines with the surefly mag. Its my understanding that an engineering change was made on the surefly to upgade/change the bearings to comply with Lycoming reliability requirements. My question is, did surefly make this change across the board to all there products or just the ones that Lycoming will be using?

The units are identical except for color and some difference in the firmware. Bearings and all the mechanical parts are identical.