1990 Legacy 4EAT to EJ20G 5mt swap

[Nü Umbrella]

Hey everyone,

 

First post here. I've been wanting to do this swap for some time. Finally with a little downtime, I was able to score a 1990 Legacy sedan in red. It's an EJ22 with the 4EAT auto, pretty nice shape. Most if not basically all the first gens in my area have around 300k miles and are total beaters by now. Still runners though. My friend is taking the EJ22 and converting his '78 VW bus to Subaru power. At the same time I'll be putting an EJ20G and 5mt into the Legacy. I want to do the JDM engine route and after going back and forth between the 20K and the 20G seems like the easier and more budget friendly swap. I found a used complete engine, ECU and wiring harness still attached to the transmission for $1,500 and I think I'm going to pull the trigger. I have been researching this for awhile and think I have most of the idiosyncrasies figured out, but I don't have a donor car, so there are some parts that I need. 5mt 1st gen driveshaft, rear diff, axles, and can't for the life of me find a slanty intercooler for the 20G (been scouring the Yahoo Japan auctions.) But I needed a little more info on this that I can't find. Rear diff, the 20G trans will be a 4.11 ratio and I know the 4EAT legacy diff is not that. 3.90 I think? So going forward, will I need a whole new rear diff carrier? Or can I just install a 4.11 diff in the existing carrier? And will I need new rear axles if I do this? What diff to use? R160? There's a wrecking yard near me that specializes in Subaru, and he'd probably have a diff out of a 2.5RS. For the front axles, would I just use the existing ones on the car already? Or will I need new front axles as well? There's a lot to consider going forward, any help/advice is very much appreciated. This is also my first Subaru. I just got a 1999 Impreza OBS for my girlfriend and every time I drive it, or any Subaru for that matter I remember how much I like them and can't help but wanting one myself lol just want something a little different.

 

Thanks in advance,

Joe

[monkeyposeur]

Don't bother with a slanty intercooler. Just use a 2006 Forester XT intercooler.

 

Get on https://bbs.legacycentral.org/

[Nü Umbrella]

Thanks, I'll sign up there. Just a quick question on the intercooler situation, I'm getting very contradicting information on the EJ20G intercooler. I read that the slanty is an air-air intercooler whilst later WRX models all had water-air intercoolers. Is the slanty air-air? And if so, I'm assuming the Forster intercooler you recommend is also air-air? If so, that's awesome as I can't find a slanty ANYWHERE.

 

Thanks,

Joe

[monkeyposeur]

The slanty is an air to air. The water-air were super rare. The Forester tmic is air to air. It's not that difficult to install one, but you have to make some modifications to get it to fit. There are lots of threads on bbslegacycentral showing how to do it.