Here are some pics of my engine build to help with ideas. Be aware that the EJ series (I dont think the EJ20 was ever in a US Subaru, but the EJ22 was) is 2 generations newer than the EA81. Its an Overhead cam EFI 2 litre, whereas the EA81 has pushrods and a carb. EJs also come in two families, earlier single cam per side or the later twin cam models.
This is the starting point, straight out of a 1997 Legacy Brighton:
The core engine was completely stripped down and I had a mechanic friend overhaul it, with new rings, bearings etc and the heads were overhauled with seats cut and all that associated work. The bolts etc were all cadmium plated before they went back in.
I initially fitted the engine with a Real World Solutions (RWS) EFI control system with individual coils,but before it flew I changed this to a Link LEM4 controller produced here in NZ. I have nothing against the RWS, but was having trouble getting the engine to run and no-one locally knew anything about the RWS, and troubleshooting when there is no significant time zone overlap wasnt working. The Link is used in motorsport extensively here, and there are plenty of very knowlegable tuning experts who make it very easy to set up.
I am Running an Autoflight 2.4 - 1 reduction drive, also NZ made (manufactured just up the road from me) driving an Ivoprop in flight adjustable prop. I have modified the cooling mainfold to incorporate a filler cap, and I am using a small radiator supposedly off an Audi. The Radiator looks draggy, but in practice the airflow though it is very smooth, and unlike a lot of other Subaru conversions with lower profile or convoluted cooling arrangements, this runs at nice stable, cool temperatures no matter what. I have added an oil cooler to the front of the engine and a remote oil filter, running off an adaptor on the factory oil cooler mount. A very useful addition is a quick drain sump plug - this definitely is worth having as it makes oil changes very quick and clean.
I wanted to use lord engine mounts to isolate the engine from the airframe, so I made up 4 alloy mounts and had these machined. To work out what was required I first built up rough mockups out of wood so that I knew where to hang things in 3D space. The lower mounts are CNC machined from 6061 alloy block by Autoflight, and attach to the factory mount pads and new points on the gearbox casing. The lower mounts also hold the radiator. The top mounts are cast in alloy and machined, and these hold the Delco alternator (rather than the standard Subaru Denso - I wanted more electrical generating capacity). I used the wooden mock up mounts to make casting patterns (which is actually quite a lot of fun to do) and these were cast and machined for me by Autoflight as well.
Following are some photos of the powerplant during build - up, whilst it still has the RWS EFI with individual Chevy coils installed. When I went to the link this chaged back to the standard subaru coil pack with a Link ignitor assembly, so the wiring on top of the engine changed. I dont have any decent pics of its current config...
The finished article installed in the Adventurer (Link fitted by this time)
I hope that gives some idea of what can be done anyway...
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