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· Registered
2004 Forester XT 4EAT
1,282 Posts
Discussion Starter · #1 ·
I have access to a '98 Forester w/the DOHC EJ25 and warped block (per the seller), due to a poorly done HG job.

Please provide any input on this scenario as I have all these parts in my possession, so this is my 1st choice:

1. '91 EJ22e block
2. '99 DOHC EJ25D Heads and intake manifold
3. JDM EJ20K Turbo Cams -shim/bucket lifters - should fit the '97-99 USDM DOHC
4. EJ22T pistons
5. TD04/VF39/etc....nothing huge.
6. STi 550cc side-feeds

I know there will be much more to this swap but curious whether the block/head combo makes any sense.

I also have a legacy turbo crossmember...rumor is it will fit the Foz.

I'm afraid my CR will be about 7.5:1, which will make it slow off boost. But since it's a 5-speed, I can play w/the power band a bit.

If you think this will work, what EM will I need? Or I should ask What EM is the easiest to make this run? I'm not worried about smog test, but don't want CELs or other drive-ability issues when it comes to sell it.

I've also considered going w/the SVX's EG33 but that means acquiring a donor car, and it may be a wiring 'challenge'...I've already bugged a couple on here about that option.

P.s. I know I can throw a '95-98 EJ22 from a Legacy in there or find another overpriced EJ25, but I'm a boost addict, so power is important!

Thanks for your time,

· Registered
99 Forester S
54 Posts
Old thread, but will post for future reference. The NA EJ22 pistons are very good pistons for turbo applications. With 46cc DOHC EJ25D heads, the CR for these pistons will be:

'96 and older EJ22 (14cc dish): 8.88:1 w/ 1.3mm head gasket
'97 and newer EJ22 (12cc dish): 9.11:1 w/ 1.3mm head gasket

This is all based on a 75mm crank. With a 79mm crank, you'd need short rods and your CR on the NA pistons would be sky high in the mid 9s.

That said, with the short rods, the EJ22T turbo pistons on this combo would net you 7.92:1...I've seen worse.

· Registered
2004 Forester XT 4EAT
1,282 Posts
Discussion Starter · #3 ·
I ended up w/the EJ22T block and EJ25D DOHC heads and EJ20K turbo cams.
This is w/the stock EJ22T head gasket.

Rumor is this is around 7.5-7.7 isn't as weak off-boost as I feared, but still wish I had more off the line.


Thanks for the info,
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