Mating v1 EJ20 to EJ25D

[sha-d]

I've posted this up on LGT and NASIOC, but havent gotten any precise advice.

So I'm really confused as to what I should do.

My Story:

Past:

Picked a 1998 Legacy 2.5GT (EJ25D) a couple weeks ago knowing that there was a timing problem and the motor wouldnt rev past 3500-4000 ; from what the owner said, I took his word and decided to fix it myself. Guy lives 80km from my place. Driving home, the engine studders but drives. Shifting at around 2-2500rpm. Im about 3 km away from home and i decide to rev it up a bit past 4000rpm to see what'll happen; at this time, I really had nothing to lose as I also got an v1 EJ20 in the deal. So I rev it up and CLING CLANG is all i heard

Got home and looked over the engine. Found out that the front crank seal is leaking and timing is BANG ON. All marks are where they're supposed to be, etc

Thoughts as to what the problem is? I'm thinking new bottom end?

Present:

The LGT is parked. I want to drive it. I can purchase myself a JDM EJ25 and swap all the accessories over and drive, but I don't want that.

I want to build the engine with STi internals. I also have a GT30R turbo which I don't mind at all using.

I have some building experience from previous projects.

Before I go ahead and start ripping the engine apart, I have a couple questions:

Questions:

Could I swap the ej20g and use all the ej25d wiring, instead of spending hours splicing wires?

Which year STi pistons and rods would I use?

Any other constructive comments are welcome,

Thank You

- Shaddy

[mike-tracy]

Decide what shortblock you want to use, tear it down and have a machine shop inspect the bores.

For the STI pistons, just get some wisecos or other custom pistons 20 or 40 thousandth overbore and have your block bored to accommodate them. Use turbo rods and crank (deciding if you want to use a phase I or II one). STi rods are overengineered enough that it's unlikely you'll ever break them.

For wiring you need to either merge or run a standalone. Your car won't be able to pass emissions due to not OBD-II compliant any more.

Another option is to use either shortblock with modern WRX heads and merge in its wiring harness with your Legacy's, this way you'll still be able to maintain OBD-II compliance & have off the shelf tuning options. It'd be much easier if you buy a wrecked wrx or know someone with one so you can get all the little things that you'll need during the swap.