The Subaru Engine Decision:


Eggenellner AircraftFirst, for liability reasons, I must say that this is not a "how you should do it" site.  If you need to learn how to install a Subaru engine, Jan Eggenfellner has put a lot of quality work into an outstanding firewall-forward package (see photo to the left).  I recommend this package be considered prior to attempting to roll-your-own.  Likewise, if you still plan to convert your own salvage automobile engine, and don't know where to start, or think you know exactly where to start, I recommend you read the 1997-1999 AirSIG (automobile engine special interest group) file archives.

When I first started flight training, my years of experience in the car business told me something was wrong with this picture.  Every plane had to have maintenance records, squawk sheets, 100hr inspections, annuals, FAA investigation when a crash occurred, etc....  Yet every time I opened the oil door I saw oil leaking.  When I started one of these Lycosaurus engines it felt like I was going to have my teeth rattled out by the vibrations.  Screws that held components in place constantly needed tightening from the torture they were being put through.  It was remarkable, to say the least, that this was the state-of-the-art in aviation.

I started investigating alternative engines.  I found a group of individuals on a forum called AirSIG.  These guys were working to show that a safe alternative existed in the automotive market.  Some previous attempts by other people using Ford and Chevy V6 engines were not working.  However, the Subaru engines had been being used in the gyro market quite successfully.  I collected a lot of valuable information while monitoring the AirSIG forum and applied a lot of it to my engine conversion.

The current technology in Subaru is far beyond that of the Lycosaurus designs in use by aviation today.  The Subaru crankshaft has five main journals.  The pistons are a cast, lightweight design.  The crankshaft, rods and pistons are balanced together before assembly into the block for smooth running and longer engine life.  Not to mention the water cooling.  Stable engine temperatures naturally lead to more even fuel burn and extremely reduced engine wear, as well as the fact that shock cooling isn't even talked about with these engines, except to say that it doesn't exist.

Back when I was developing my initial engine conversion, companies that were developing their packages were still pretty green at it.  I didn't have the money and I had lots of time to use my experience to make this work.  So I started piecing together what I needed to make the Subaru engine work in my airplane.




The links below show brief descriptions of each solution:

  1. Subaru Engine Mount
  2. Cooling System
  3. Induction and Exhaust
  4. Electronic Fuel Injection/Ignition
  5. Fuel Delivery System
  6. Prop Speed Reduction Unit
  7. Propeller
  8. Soob EFI Research Library

Click here to go to a picture gallery of the current, flying, firewall forward.