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yeah the 255 is semi-closed...its the exact same block as the 257 just slightly different internals and different heads
 

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If the same holds true from the EJ205 and EJ207 comparisons. Then I'd say that the EJ257 probably has some forged internals.
Ever since the version 8, neither of those engines have had forged internals. v7 did. They're hypereutectic (unless they've changed in the past year or so).

Also, I'm not sure the ports on the sti heads are any bigger...
 

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Good enough then. Its the N/A engines that are open deck. I was getting my info off 2.5rs.com or whatever.

WReXd: Thanks man. I don't know the versions well. So, thanks for clarifying stuff. !Thumbs Up
 

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Ever since the version 8, neither of those engines have had forged internals. v7 did. They're hypereutectic (unless they've changed in the past year or so).

Also, I'm not sure the ports on the sti heads are any bigger...
I know this is old, but this thread was one of the top 5 results on google. I'd like to set the record straight.

Both the ej255 and ej257 have hyper-cast pistons (hypereutectic). But... The rods are actually forged. Crawford actually claims that with just forged pistons, the ej255/7 can both handle up to 500whp.

The ej255 heads actually flow better but have a shallower dishing. The ej257 doesn't flow quite as well, but has deeper dishing and with the ej257 pistons dome... a lower compression ratio.
 

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Yeah, over the years I've learned a lot more and I put up some bad info up there. But, at lot of it was corrected. Thanks for information though Sinister. ;)
 
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