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Discussion Starter · #1 ·
Wondering if anyone can help me out.
I have a 2009 WRX. Blew a rod so need to replace the engine.
Upon reading around I think my WRX has the ej255. I was thinking maybe I could direct swap with an STI ej257.
Is this a direct swap???
Any advice would be appreciated!
 

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Yes and no.

The 257 is directly swapable in the sense it's the same block and everything fits.

It has different pistons lowering the compression ratio from the 255 so you may need to find a tuning solution.
 

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Discussion Starter · #3 ·
Thanks for your response.
I have an aftermarket Cobb intake and turbo. Probably why I blew the rod.
What if I drop in the STI engine and get the Cobb Access Port for tuning. Would that be a solution?
My thought here is, if I need to drop in a new engine, might as well increase performance a bit. And I thought maybe the ej257 might pair better with the Cobb turbo.
I don’t have the time or space to properly rebuild the engine with forged pistons etc...
I have some one that will swap the engine for me so I need to stick with this option.
 

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I don't know if Cobb has off the shelf tunes for that particular path, you may still have to have someone tune the vehicle.

I would contact them and ask.
 

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I don't know of any additional performance or durability to be had. I'm actually not sure what the compression ratio will change to as the wrx heads are different than the STI heads. Coupled with the deeper dish pistons the STI has a lower compression ratio. It may work out to be similar with the 255 heads I'm not sure.

At the end of the day, they are basically identical except for the piston dish. Neither has forged pistons.
 
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