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Not saying they won't fit, but you have to check the diameter of the ones you have versus your actual bore diameter.

This will insure that you will get the best fit. An A piston in a B bore will leave more room for the piston to wiggle, accentuating the possible of getting piston slap. On the other side, a B piston in an A bore with std rings will lead to undue wear of the rings.

 

O.

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99 EJ25D block, crank, rods ?

 

first, is it in fact a 99 ej25d block? (count the engine to trans bolts)

if yes, then  it is in fact already a phase 2 block, ej251 .

 

the 99 forester was / is a phase 2,  ej251 SOHC engine. (maybe ej253 depending on the trans, but the same block)

the 99 outback and GT were / are a hybrid engine from the factory,

ej251 phase 2 block with ej25d DOHC heads and intake.

 

i'm not sure what the internals are,

except to say the phase 2 blocks must have the phase 2 crank with the thrust bearing in the 5th position.

Edited by johnceggleston
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there is some concern that the 251 block and pistons may interfere with the valves of the ej25d heads.

and it is recommended that a thicker head gasket is used to eliminate that possibility.

and i don't know if this concern is based on experience or speculation.

but i do know you can use an ej251 block, 00 - 04 as a replacement for an ej25D, 96 - 98 block.

 

but if the turbo head gasket is thicker, i would use that just in case.

of course, the thicker gasket may offset any gain in compression from using the 251 block and pistons.

 

what heads are you planning on using?

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Yes we used the 25d rods, it was a 97 shortblock and they went in no problem. No protrusion from the cyl like the 25d normally does.

 

The 99 25d uses the same pistons as the 97/98, as long as you're sure the pistons are 251 then you are good. Use some STi head gaskets and 25d heads and enjoy high compression.

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