Sorry for veering off original topic. I’ll answer earlier posted question and go-around.
I think most of the issues surrounding failures of conversions were due to lack of resources in their development. Many early conversions were simply experimenters taking engines from a junk yard. Electronic fuel injection systems and their programming for car mission, including anti theft and limp modes that would shut the engine off or limit RPM to just above idle, was also a factor early on. Most failures were not caused by mechanical engine issues but ignition and fuel delivery component failures and lack of any meaningful redundancy.
Concerns RE single FADEC spot on with automotive systems. The system I have in c172 is a redundant EFI system. Whereas most EFI systems use throttle by wire like a car gas pedal that sends an electrical signal to a servo on the engine, my system uses the original throttle cable to manually move the throttle valve. There are 2 independent EFI systems as well, both with own battery, computer, critical sensors, fuel pump, fuel filter and pressure regulator. The back up system is tested before takeoff by depowering the main system and checking that engine reignites within 1/2 second....which is easily done during taxi by pushing test button. There is no need to stop for engine run-up unless leaded AVGAS is used and spark plugs need to be heated up (to burn off carbon). The computers are Delphi and have been used in cars, trucks, boats, industrial equipment and military engines for over a decade. The same engineering firm that developed the calibrations for this exact engine controller model for General Motors also developed this system specifically for the aircraft mission. The system has several layers of redundancy......I can fail the main system in flight with test button, and the aux system restores it within .5 seconds with the prop windmilling. It’s pretty cool. I also like that there’s no mixture or carb heat.
It come as as a firewall forward kit for the c172 and 182, but it’s not available in US due to liability issues. The manufacturer started FAA cert process but could not get any manufacturers liability insurance so there was no point. My Skyhawk is experimental. There’s photos of the engine at corsairv8.com
RE PSRU, you are correct that’s it’s been a historical problem. The reasons for this are somewhat complicated. The unit on Corsair kit V8 is a made by an long established airboat gearbox manufacturer that’s modified for the aircraft. It’s rated and proven at more than twice the torque and HP of the original aircraft engine limit, but this overbuilt approach adds weight. I’ve read some home built PSRUs failed because the engine produced more torque than box was rated, which is easy to do with a 500 HP V8....my engine is flat rated to a max of 220 HP which is max the c172 was ever certified to.
The early version had a chip and temp detector that would display a warning in the digital display. I think most design failures were attributed to shaft fatigue caused by cylinder compression pulses and inertia of the gears amplifying the torsion.
RE prop: it’s a Sensenich wood composite. There’s a photo on the website
RE auto conversions worth less on RVs. I’m not familiar with resale values but expect so. The conversions out there I researched are mostly home built and lack meaningful redundancy, and auto conversions have a bad rep from early on experiences in the experimental communities. I spoke with more than one pilot that experienced engine failures. For me, I had a over TBO original engine that was going to cost me about $29k to overhaul, and likely needed a new prop, and the airframe was only worth about $10k. The V8 alternative made sense, mostly because operating cost went from $60/hr to about $19 so I didn’t feel as guilty flying it. After selling original engine and prop, it cost me about same as overhaul but everything was new. A buddy used it to build time to get his ATP for a fraction of the $125/hr rental he was using. So, it’s probably not for everybody, but it works for me. Again, sorry for getting off original topic.
so, to answer original post, Yes, I would and did consider V8 or other option if there is some real meaningful engineering and mods to address conversion issues. Flying a 40 year old antique at its unreasonable operating cost didn’t make sense and greatly reduced how much I flew it. The extra features as a simple start button, lack of mixture and carb heat, burning non-leaded gas and eliminating a 5 min run up appealed to me. GA pistons are stuck in the 1950s with absurd op cost and we need to find alternative solutions. If not an auto conversion, than some other engine alternative should be considered.
