Hello,

i have a 1994 Impreza L AWD wagon with a EJ 1.8. Currently it has 310k miles and it’s knocking, I wanted to replace my engine and I wanted to know what engine would bolt up to the stock transmission. Will any other EJ engine fit? I’m new to the Subaru scene so I’m not sure it’s my first Subaru Any info will help thanks..

Any EJ18 will fit. 

1995 and earlier EJ22 will work if you bolt the EJ18 intake manifold to it or swap the EJ18 intake wiring harness onto the EJ22 manifold.  1995 auto EJ22s have EGR, 1995 manuals do not.  Ignore it, remove EGR, or Work around it or buy accordingly if that scares you.  

1996+ EJ22 has single port exhaust and won’t work unless you use a single port exhaust manifold as well.  Same EGR points apply as 1995. 

EJ25 will work if you swap the EJ18 intake manifold wiring harness to the EJ25 intake manifold. 

If you want to avoid wiring issues - use your EJ18 intake manifold, 1995 and earlier EJ22heads and an EJ25 block. 

Just a side-note. the EJ18 EGR pipe may not work/fit right on an EJ22 (I've never had/worked on one).

Here's how to bypass it on an EJ22, but not sure if the EJ18 'likes it'.

 

Also, RS25.com is dedicated to Imprezas and may have this covered, too.