Swapping EJ20E for a Forester EJ20G?

[josh2109]

Hi folks,

So I've picked up a Legacy wagon with a suspected head gasket failure. The plan was to repair the engine and then run the car as a reliable wagon for carting the dogs round in. But... I noticed on ebay that a chap locally is selling the EJ20G out of his JDM Forester, plus loom, ECU, intercooler and so on. The price is reasonable, and I'm seriously tempted. Here's where my knowledge runs out unfortunately.

So far, from the web I've been able to gleam that the Forester EJ20G is an OBD-II engine, so straight off the bat that is something that could make my life difficult. However, I've done a swap on a Honda before where swapping an OBD-II engine into an OBD-1 car was achievable by swapping over the alternator, injectors, distributor plus a couple of other bits, and aside from the usual joys of spannering on a car that's 20+ years old it was a fairly straightforward job

So I guess my question is, if I use the EJ20G out of a forester, can I use the wiring loom, ancillaries, sensors and loom from a classic Impreza in order to make the swap more straightforward from an electrical point of view?

Really appreciate any input on this one, as my knowledge of Subaru engines is shaky at best!

I'm not sure if it's relevant, but my car is a '95 registered BJ wagon with an EJ20E engine, I suspect it was probably built in '94.

Cheers,
Josh

[Alphius]

For a swap like that you'll likely need to do what's called a wiring merge. You take the body and engine harnesses from both cars and cut all the old engine harness out of your body harness, then cut all the body harness out of the donor's engine harness. You'll be left with 20-30 cut wires for different functions that cross between the body and engine harnesses. You'll connect those wires from the donor engine harness to your car's stripped down body harness and the engine should run if you get it right.

Not a job for the faint of heart, but it's doable. You would want to have access to the FSM (Factory Service Manual) for both the donor and receiving vehicles. Many of us here (including myself) and in other communities have done similar swaps. You won't find much information on this forum regarding your specific engines as we never got the EJ20E or the EJ20G or any turbo classic Imprezas/turbo SF Foresters.

[mike-tracy]

Hi Josh, the ej20g forester is most similar to the version 3 and 4 Impreza. Despite the engine code it is not an ej20g like the legacy or early imprezas got.

Mechanically it will bolt up, but the wiring loom must be merged/spliced into yours and you will be running its ecu. Its not as simple as a honda from the electrical side.

Since you have to merge wiring, the obd part isn't an issue.

[mike-tracy]

You are a Ninja, Alphius!

[josh2109]

Cheers chaps! So not quite as simple as I had hoped, but still achievable. As it stands I'm looking at about £200-300 all in for an engine, gearbox, rear diff, loom and ECU and other gubbins so I'm thinking it's probably a worthwhile project, as the car stands me at barely anything as it is and the engine needs to be rebuilt anyway.

RE the wiring loom merge, it is something I've done before albeit on a much simpler car and engine. I have a mk2 Golf which I swapped the 1.6l carby engine out of and replaced with a 2l fuel injected engine from a mk3. That was a case of establishing what each sensor on the mk3 engine was, marking the loom, removing the rest of it, extending it to fit the wiring run on the mk2, and then splicing in the few bits from the body loom of the mk2 which I was using such as the ignition coil, starter motor and so on. It wasn't a fun job, but working slowly and methodically paid dividends.

The auction on the EJ20G ends today so I'll keep you guys posted.

[josh2109]

Well I bought the EJ20G out the forester for £156 - guess I'm going to press down this route then lol. The bloke who I bought the engine from has the loom and ECU amongst some other bits so hopefully I'll be able to get a good deal on the rest of the bits needed to run the engine. The engine comes with an auto box which is no use to me, I'll be sticking that back on eBay and hunting down the gearbox and rear diff from a turbo Impreza - the going rate seems to be about £150 for the pair over here.

I'm looking forward to getting started!

[kimokalihi]

Wow that's a steal of a deal. I am running that engine from a 97 jdm forester in my 91 legacy with an obd1 Sti ecu. I had to use my cars throttle body due to the different tps on the obd1 cars and modify the engine harness to have the proper plug for the tps. I also had to convert my ignition wiring so I could run coil on plug and swap a wire under the dash at the ecu and merge another and remove a couple but other than that it was pretty easy. I don't know how it will be with your car being a gen 2 but you can check my build journal if you'd like. It's in my signature below and goes through everything I've done with my car.

[Alphius]

Hey Kimo, his car is a Gen1 N/A.

You'll lose the selectable 4wd and hi-lo by going to a turbo gearbox!
Granted, fulltime AWD will be better, but I'd miss the dual range personally. Haha.

[josh2109]

Wow that's a steal of a deal. I am running that engine from a 97 jdm forester in my 91 legacy with an obd1 Sti ecu. I had to use my cars throttle body due to the different tps on the obd1 cars and modify the engine harness to have the proper plug for the tps. I also had to convert my ignition wiring so I could run coil on plug and swap a wire under the dash at the ecu and merge another and remove a couple but other than that it was pretty easy. I don't know how it will be with your car being a gen 2 but you can check my build journal if you'd like. It's in my signature below and goes through everything I've done with my car.

Your build thread was part of what inspired me to go about swapping out the engine from my wagon! I was reading through it whilst keeping an eye on the auction for the Legacy I picked up It looks like a wealth of information though, I'll definitely be leafing through it whilst working on my car I should think.

I imagine my car is OBD1 as well, which is why I was considering going down the route of sourcing an ECU from an Impreza turbo - there's so many of them here in the UK and parts off of them are fairly cheap.

I think the first thing for me to do is establish the pinouts from my existing ECU versus the donor car's and then work from there.

Hey Kimo, his car is a Gen1 N/A.

You'll lose the selectable 4wd and hi-lo by going to a turbo gearbox!
Granted, fulltime AWD will be better, but I'd miss the dual range personally. Haha.

Yeah, I appreciate I'll lose that, and to be honest I think the dual range gearbox is one of the coolest quirks of the car so it's a bit gutting. The problem is that in 2wd it's running FWD, and I think to get the best out of the car and engine it's really going to need to be running in AWD - I'd keep the stock box if it could run on tarmac in 4wd, but apparently it can't That said I don't know how long the original gearbox would last with the hike in power and torque. I'd definitely have stuck with the stock box until it died if it ran as RWD when in 2wd mode though

[Alphius]

You could find a fulltime AWD dual range box from a 2.0L SF Forester or Impreza wagon over there, I know that. Plenty of people on this side of the pond have run decent amounts of power through N/A transmissions; as long as you don't drive like a fool it'll hold up fine. The turbo 5-speeds (especially classic Impreza/Legacy boxes) aren't much stronger and will break with abuse as well.

[josh2109]

So yesterday I picked up the new engine!



In addition to the engine I also got the whole body loom from the Forester, plus ignition barel, ECU, intercooler and a few other bits for £200 all in. So far I'm quite pleased with how far my budget is going, will be interesting to see if it actually all works once it's been put together

You could find a fulltime AWD dual range box from a 2.0L SF Forester or Impreza wagon over there, I know that. Plenty of people on this side of the pond have run decent amounts of power through N/A transmissions; as long as you don't drive like a fool it'll hold up fine. The turbo 5-speeds (especially classic Impreza/Legacy boxes) aren't much stronger and will break with abuse as well.

That's interesting to know - it's just a real shame the standard box on my wagon is FWD when it's in 2wd mode. if it was RWD I could live with not having AWD for launching. I can't live with FWD though, I don't think it's sensible putting down a lot of power soley through the wheels that you're steering with. Give me oversteer instead of understeer any day of the week!!

[Alphius]

In addition to the engine I also got the whole body loom from the Forester, plus ignition barel, ECU, intercooler and a few other bits for £200 all in. So far I'm quite pleased with how far my budget is going, will be interesting to see if it actually all works once it's been put together

Good deal! Sounds like you have everything you'll need to get the swap done from a wiring and ECU perspective. I don't have any service manuals for foreign market Subarus or I'd have your back on the necessary wiring harness info.

I just bought and imported a dual range AWD Forester box for my wife's 2002 Outback. We didn't get them here at all; it was very expensive. Now I'm working on finding the dual range shift lever and console trim to make it all look factory. Maybe if you find one from a Gen3 Outback you can snag the console and shifter assembly for me too.

Since I've been doing some research on the dual range, I found that basically all of your later model non-turbo wagons in Legacy, Outback, Impreza and Forester guise should have the fulltime AWD dual range box. If you get one from a Legacy or Impreza, the speedometer gear will be correct and your speedo will read right, but if you get one from an Outback or Forester the speedo output will be setup to read properly for the larger tire size on those cars and your speedo will not be accurate. Keep that in mind if you do go this way. Aside from that difference, they should all be a bolt-in swap for your car; even the hydraulic vs cable clutch transmissions can be converted to work with either clutch type easily.