FlyEFII System32 vs SDS

FlyEFII (or EFII) started selling electronic engine management kits for Lycoming engines in 2008.
The legacy EFII kits used SDS supplied electronics until 2017. The desire for better designed, more modern and more capable electronics inspired EFII to start the development of the System32 engine management system in 2017. System32 went into full production in early 2019 with close to 150 aircraft flying or under construction less than a year later. System32 has been adopted by multiple military, UAV, and major engine suppliers. System32 is made in the USA.
SDS sells a 1990s technology engine management system. This product used to be the DIY, entry level engine computer product in the automotive after market until the Megasquirt product took over this market segment (
SDS now markets this product to the experimental aircraft market. The original technology is still in use in various repackaged versions. SDS products are made in Canada.
Number of System32 installations in line to “upgrade” to SDS products – zero.
Number of SDS installations in line to upgrade to System32 – many.
System32 ECUs use a high speed 32 bit RISC processor with approximately 75 times the processing power of the legacy ECU.
SDS ECUs use a 1990s technology processor. Wikipedia calls this processor an 8/16 bit architecture. This processor has an 8 bit core with a 16 bit datapath added to it. (look up “68HC12 Wiki”, the processor used by SDS is part of this family)
System32 ECUs have fully interpolated 3D mapping of fuel and ignition functions. This allows for easy and powerful tuning. Maps can be loaded via SD card or modified through the Controller interface.
SDS ECUs use a data intensive mapping scheme required to work around processor limitations.
Mapping jumps from point to point – processor does not have enough speed to calculate intermediate values in between mapping points.
System32 provides semi-sequential fuel delivery timed to intake valve operation.

  • Better starting
  • Smoother operation
  • Better throttle response
SDS ECUs use batch fire fuel delivery not timed to intake valve operation.
System32 ECUs have field upgradeable firmware via SD card.
SDS firmware upgrades requires removing ECUs from aircraft and sending them to Canada.
System32 ECUs have a wide operating voltage range, 3.5v to 40v. This wide range prevents ECU brown out during engine cranking and provides extra ECU protection in the event of voltage regulator failure.
SDS ECUs have an operating voltage range of 7v to 22v.
System32 ECUs use a high EMI immunity 4 layer gold plated circuit board with RF filters on every input and output.
SDS ECUs have limited EMI resistance, 2 layer circuit board, minimal RF filtering. Multiple customers (especially on composite aircraft) have experienced RF induced ECU interruption during radio transmissions.
System32 provides integral data recording of all system functions onto Controller SD card.
SDS requires a PC interface adapter and laptop to record data.
The System32 Controller utilizes a modern full color, sunlight readable LCD display with automatic brightness control .
SDS uses a low cost 2 line monochrome LCD display. Susceptible to damage from exposure to direct sunlight. No provision for automatic brightness control.
All System32 wire harnesses are made from 100% Tefzel aircraft wire with integral circular connectors for firewall penetration. Every power circuit within the harness is individually protected by a fusible link within the harness. Harnesses are 90% factory terminated.
SDS base wire harnesses are made from multi conductor vinyl sleeved telephone cord. Optional Tefzel wiring. No individual protection on power wires except break out to circuit breakers. Customer termination required on most circuits. (Wire harness construction is a common customer complaint).
All System32 kits are fully redundant, dual ECU systems. Injector control is hard wired (no relays) and switchable between ECUs via solid state electronics.
SDS base systems are single ECU, non-redundant systems.
Dual ECU systems require a relay bank to switch injector control between ECUs.
The System32 cold fuel rail design delivers a continuous supply of cold fuel directly to each injector. Injectors are cooled on one end by the fuel rail and on the other end by the induction air. Fuel lines are not located in the after shut down heat soak path of the cylinders.
SDS fuel injectors sit at the end of one way fuel lines and are located above the cylinders. This subjects the injectors and one way fuel lines to heat soak after engine shut down. This can cause fuel vaporization leading to hot start issues and long term failure of injector o-ring seals.
System32 ignition coils are mounted on mechanically sound block plates on the rear of the engine.
SDS ignition coils are cantilevered on mounting plates. Some coils are mounted above the engine heat soak area. This forces the coil to endure an excessive thermal cycle after engine shut down and places an obstruction in the cooling air path above the engine.
System32 kits include a high quality Aeromotive fuel pressure regulator that has been internally drilled with a bypass orifice to allow for quick system re-prime in case a fuel tank is run dry allowing air to enter the fuel system.
SDS includes a low cost Borla (a muffler manufacturer) fuel pressure regulator. Does not include a re-prime orifice.
With System32, the pilot only has to deal with a single integrated system – the Controller communicates with both ECUs simultaneously to make any tuning or configuration changes. This dramatically simplifies set up and tuning.
SDS ECUs have to be programmed individually.
System32 kits include easy to maintain disposable fuel filters with AN-6 fittings. Aeromotive fuel filters are recommended for customers who prefer serviceable filters.
SDS includes Holley serviceable fuel filters
System32 Crank Trigger magnets:
Lycoming – magnets are installed in customer flywheel in precision locations at EFII’s in-house machine shop. This service is included in the kit price.
Continental – magnets are located in a billet magnet ring that clamps around the prop flange.
SDS Crank Trigger magnets:
Lycoming – customer must drill flywheel and install magnets themselves, timing must be verified with a timing light.
Continental – customer must drill holes in the propeller bolts and glue magnets into the bolts.
FlyEFII Bus Manager
The Bus Manager is a companion product to System32. This provides an easy solution to creating a redundant 12V bus to protect the power to the engine electronics. The Bus Manager also manages the backup electric fuel pump and allows engine starting off of either battery.
SDS does not make a bus power protection product.