Subaru army, let's talk frankenmotors.

I'm about to do a trans swap on my EJ22 Subaru-powered Vanagon, and a friend tol' me about these frankenmotors. Since I'll have it out...

For those who don't have the knowledge, that's a 2.5 with a set of heads from a 2.2. The end result is apparently a bunch of torque and the ability to run on the 2.2's engine management. I'm mostly interested in low end grunt and reliability, not making maximum power at high RPM. Boost is not planned

I've come up with a fairly clean 1999 Outback that has bent valves, so it's the perfect bottom end donor. Turns out that's a bit of an oddball motor, half Phase 1 and half Phase 2. I've come across these Phase 1 DOHCs before and seen problems with oil passages.

Any suggestions for reliability? Words of wisdom? Should I just fix the Outback and sell it and move on to something else?

   KT there will be a subi at the Challenge with a Freakinmotor.

 That Is all that can be said.

I can’t remember if the 99 Outback was the DOHC EJ25D or not, but generally people stay away from those. When the HG’s go on those they leak internally and fail catastrophically. I however had one that had over 400K kms on it when I sold it. From what I understand, if you fix the HG’s properly they will run a long time. Since you would be changing the heads, this likely would not be an issue. 

I think you would be better off with a 2000-up block, but I have more experience with the stock engines.

The 99 Outback (and only the 1999 Outback, according to Wikipedia) is a hybrid DOHC EJ25D. It has the Phase 2 casing, crank and rods but Phase 1 pistons and DOHC. I don't know what part of the engine is viewed as responsible for the head gaskets, but Wikipedia also seems to think the first SOHCs weren't much better in that regard.

I'll probably crack the case and swap out the bearings while I have the engine out, just because. And of course it'll get a timing belt (it has to!) and Cometic head gaskets. Cometic makes a MLS gasket specifically for this swap.

Will you be using the heads from your existing EJ22?

What are you looking to spend. EJ20T and EJ25T motors are out there cheap if you look and they are not a 100% drop in but OEM design and more power.

Why not ej20 with 1.8 heads? Big NA compression.  

I am planning to reuse the EJ22 heads off my existing engine. This is not a big power application - see the first post. I want torque and reliability. This is also going in the back end of a camper, and honestly I don't want the hassles of having to build turbo plumbing. This is basically a crime of opportunity - I'll have the engine out, so it seems straightforward to simple change out the short block. I don't want to screw around with engine management, as this is more of a self-propelled house than a crazed project. 

Why not EJ20 with 1.8 heads? Because that's basically what I'm looking to do, only 25% bigger. Also, the van is already running EJ22 engine management and I have EJ22 heads.

So let's take the EJ22 heads and EJ22 engine management and lack of boost as constraints. Does anyone have experience with the EJ25/EJ22 frankenmotor?

Make sure you use a MLS head gasket from the turbo motors and not the composite gaskets from the NA. That's supposed to be the trick to fix the HG issues.

"Not all EJ25 blocks are the same - but the frankenmotor generally consists of the EJ25D block with EJ22E heads (from any year you desire). The reason the 25D is used is because the pistons are taller and provide higher compression than the EJ251 and up. That and the EJ25D is the cheapest of the 2.5 blocks. "

Check out www.ultimatesubaru.org

So your 99 EJ25D block should be fine.  You should likely run 91 octane in it.

I haven't looked at them for a while but it never really seemed like any of them stayed together all that long. Could have been cause they were junkyard parts or could be a different issue. Deltacam can make you a  torque grind for the 2.2 and the obd1 can be tuned but I doubt you are regularly running past 4k in the van.

Have a friend with a 2.5 (STI) block with WRX heads. 

But he has weisco 14:1 pistons and BOOOST on E85...

A very entertaining drive.

I believe he is on a hacked stock ECU that was dyno tuned, He is a subaru tech and I would be glad to reach out to him (or put you in touch with him) if you have any questions.

I actually have a pretty good Scuabru shop in town, but like all Subaru guys they're boost heads. Naturally aspirated power just isn't a normal thing around here. I could probably get them to tune the ECU if necessary.

Head gaskets will be Cometic MLS. Man, Subaru heads look weird.

I know you’re looking for that extra .5 of displacement (who would blame you?) but, so you know, in case worse comes to worse, 1.8 heads work with 2.2 peripherals. Or so I’ve been told. Never performed that Frankenstein myself. 

If you swap that J for a G, and add 50%, you get a nice engine called the EG33.

I'll even sell you one at the challenge. 

mck1117 said:

If you swap that J for a G, and add 50%, you get a nice engine called the EG33.

I'll even sell you one at the challenge. 

This is a much better idea IMO.  And it'll sound better too 

Followup, because there is NEVER followup on Frankenmotor discussions. Note that when I started this thread, the concept was theoretical. Then the EJ22 done gone blowed up in the middle of Utah so I had to do something. And I had this EJ25 bottom end already and a trashed EJ22 bottom end.

Short version: the engine is in the Vanagon and working well. It is almost literally a 2.5 short block with everything else from the 2.2.

Long version, assuming I remember all the details. This was a very long project because I moved in the middle of it and the machine shop had some parts for a year and well, too many cars.

I ended up pulling apart the 2.5 short block which is a good thing because someone had pulled the pin on the Subaru hand grenade. It was about to go, the only reason it didn't suffer a catastrophic failure was because a broken accessory belt took out the timing belt and bent the valves first. So I rebuilt the bottom end, which means I took the block and replaced everything inside. It's all OE Subaru, but now it's running STI stuff because why not, it's no more expensive. The crank was damaged and a new one was less expensive than fixing the old one. Pistons were tired so they got changed, the rods were swapped  because I had no confidence in the take-outs from the 2.5 - or maybe they were damaged, I don't recall. I do recall that OE Subaru parts are pretty cheap compared to forged Miata parts :) So it's got a new crank along with pistons, rods and the oil pump and the other usual stuff. Almost everything is normal EJ25 in the bottom end other than the tensioner. Or is it a middle end on a Subaru?

Heads are the SOHC EJ22 units cleaned up. The machine shop made disparaging noises when I dropped them off because blah blah 600 hp turbo and who wants EJ22 heads? Well, I do, shut up and do the work I'm paying you for. They are unmodified.

Head gasket is the MLS Frankenmotor gasket available from Cometic, part H1631SPK051S.

Timing belt kit was EJ25 for the 1998-99 Legacy, which IIRC matches the SOHC heads and the other generational parts from the short block. I did swap over the timing belt tensioner bracket from the SOHC EJ22 on to my DOHC EJ25 block and used the old-school tensioner instead of the newer design. I suspect I could have sourced a newer bracket from a SOHC EJ25 but I was trying to build all this with the parts I had on hand. There were some misadventures while installing the timing belt after repairing a poorly installed cam seal because I'm a bit of an idiot, but I got through it.

Intake manifold is the EJ22 unit because that was the easiest way to deal with the fact that the car already had EJ22 engine management. That was an important factor in the Frankenmotor decision, going to a 6 cylinder would have involved trying to reverse-engineer a swapped wiring harness done by someone else and reswapping it. I do have the EJ25 electronics on hand in case I decide to update, but I don't have a strong reason why.

End result: A very perky engine. It's not a 600 hp turbo monster but it's perfect for the use case with lots of torque right where I need it in normal driving. It is noticeably stronger than the old stock 2.2. On the highway, I actually have to pay attention to keep it below 80 when cruising at 5000' above sea level. Fuel efficiency does not appear to have changed, although I feed it premium now due to the roughly 11:1 compression. And I recently discovered that the throttle cable lash-up doesn't even allow me to reach WOT, so I have a power upgrade in my future :)

Picture of the almost-assembled setup. I note now that I have the crank in the wrong position for setting the timing belt, foreshadowing there...

Keith Tanner said:

Heads are the SOHC EJ22 units cleaned up. The machine shop made disparaging noises when I dropped them off because blah blah 600 hp turbo and who wants EJ22 heads? Well, I do, shut up and do the work I'm paying you for. They are unmodified.

I imagine you standing in the shop saying "Do not not want my money for some reason?" to a cash register droog who's now stammering because nobody cares about his trash opinion lmao

GIRTHQUAKE said:

Keith Tanner said:

Heads are the SOHC EJ22 units cleaned up. The machine shop made disparaging noises when I dropped them off because blah blah 600 hp turbo and who wants EJ22 heads? Well, I do, shut up and do the work I'm paying you for. They are unmodified.

I imagine you standing in the shop saying "Do not not want my money for some reason?" to a cash register droog who's now stammering because nobody cares about his trash opinion lmao

The good thing to showing up at a machine shop with a ported Mopar slant six head is that it's such an obviously insane move that trying to talk you into using different parts is going to go about as well as showing a flat earther a globe. EJ22 heads might suggest the builder has just enough of a grasp on reality to reply to reason (except the machinist failed to realize the reason for using the heads in the first place).

This is very cool.

I have to say, I loved my NA 2.2 Impreza.  Ot was a fun, torquey motor that kicked butt at a bunch of rallycrosses and made an awesome daily.

A non rusty pre 01 Impreza sedan with a really good suspension is still a car I'd love to have and keep for a lot ng time

You can't talk to Subaru nerds about a frankenmotor before it turns into a 600 hp turbo discussion. It's a compulsion, made worse by the fact that this machinist is actually responsible for a Subaru specialty shop that builds 600 hp turbo Subarus. We were able to work around our differences about my heads, although maybe that's why it took so long to do the work :)

I certainly could have built this cheaper and faster if I was doing a Lemons or Challenge-style build, but I wanted rock solid reliability if at all possible because of how this vehicle gets used. Thus the completely rebuilt/refreshed bottom end. Really, given a running EJ25, you could put one of these together in a weekend. Heck, you could probably do it as part of a head gasket swap on the first generation 2.5 RS.

Nice write up, Keith. I've been debating this setup for a dedicated NA rallycross car.

I have a friend who races Lemons with these things, he's much better at it than I am. I can relay questions :)

The timing belt kit bothers me. It's a Continental TB277LK2, which fits the earlier DOHC EJ25s and which matches the short block. Did I get a second belt for the SOHC, and purchased the DOHC belt because it had everything else I needed (other than a surplus tensioner that is probably for sale if anyone wants it)? I have no idea. I don't see any records of that. I'm going to have to go pull out the box of leftover bits. There might be a belt in there, I think I remember one. But my life is full of timing belts.

Also, holy price jumps batman. That kit was about 50% less in 2018.

The compression bump won't be too much of an issue above 5,000 feet where cylinder pressure is at a premium.  You could probably run it at lower octane most of the time.

That's certainly true, but I'll check to see if the engine has a knock sensor first before I start taking any chances :) Our high octane is only 91, like most of the area west of the Rockies.

Edit: it should, but I don't recall if there is one actually installed on this swapped setup. I would have installed it on the engine but I don't recall that familiar detail amongst the haze of Subaru weirdness. There's at least one wire with a random unidentified switch, future plans include trying to figure out what that does.