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Old 04-12-2018, 09:35 PM   #26
turboL
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Default Differences in ej253 shortblock versus ej257?

Read this thread, countless others. Measured rod length 255/253. Measured wrist pin to piston top height 255/253. Also wrist pin diameter. (Wrote down the specs at work will add later). Iím going to throw together a 255 block, 255/253 crank (they are identical), 255 rods and 253 pistons with 253 heads. Havenít figured what headgasket to use yet. It will all go in a 97 Impreza running the 05 RS ecu/manifold with a 16G turbo. Weíll see how it goes.

Pretty much the 255 rods are shorter than the 253 so itíll drop comp slightly.
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Last edited by turboL; 04-12-2018 at 10:25 PM.
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Old 04-28-2018, 07:35 AM   #27
pcampbell
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Default Differences in ej253 shortblock versus ej257?

Quote:
Originally Posted by turboL View Post
Read this thread, countless others. Measured rod length 255/253. Measured wrist pin to piston top height 255/253. Also wrist pin diameter. (Wrote down the specs at work will add later). Iím going to throw together a 255 block, 255/253 crank (they are identical), 255 rods and 253 pistons with 253 heads. Havenít figured what headgasket to use yet. It will all go in a 97 Impreza running the 05 RS ecu/manifold with a 16G turbo. Weíll see how it goes.

Pretty much the 255 rods are shorter than the 253 so itíll drop comp slightly.


Iíve never done this but most people are using 257/255 rods and pistons on 253 heads not 253 pistons.

Some people modify the 257 rods for 253 pistons but why not go with 257 both. I think 257 bottom with 253 heads is like 9:1ish?

What will you get with 253 pistons over 257 and are they strong enough?

Last edited by pcampbell; 04-28-2018 at 01:22 PM.
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Old 05-01-2018, 09:29 AM   #28
pcampbell
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Default Differences in ej253 shortblock versus ej257?

What power are the stock 253 pistons good for ? Rods? Iíve seen 300-330hp in a few spots.
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Old 02-14-2019, 11:33 AM   #29
Gamil
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I'm also looking at using an EJ257 block to rebuild an EJ253 for a 2011 OBS.

Is the EJ257 block the same width? ie can I use original intake manifold and exhaust? I'm working out details for a high compression NA build.

I don't want to turbo, it's not a DD, but it does need to be streetable.
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Old 02-14-2019, 04:04 PM   #30
pcampbell
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Default Differences in ej253 shortblock versus ej257?

Ej257 block is fine. It needs a different coolant crossover pipe and has 1 more crankcase breather on the driver side. But you will end up with lower compression if you use 257
Pistons. For High Cr Na there is no need to use anything but a 253 block unless you happen to have a 257 block.

The exhaust and intake bolt to the heads. So the block used is not relevant there.
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Old 02-15-2019, 11:32 PM   #31
Gamil
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Thx. Have you gotten any new info on the stock ej253 rods for HC use? New pistons are the only way to get a higher CR, I think, and they're all forged. But, if factory rods are good up to 12:1 or higher, then no need to spend $400 on rods
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Old 02-16-2019, 06:49 AM   #32
pcampbell
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Default Differences in ej253 shortblock versus ej257?

I really have no idea but my stock 2005 ej253 rods are holding up to roughly 300 whp. Keep in mind rods come in 130.5 and 131.5mm lengths and both were available in the ej253 depending on year. So you want to use the correct ones to work with your new pistons. What year is yours? Which pistons did you go with?

Last edited by pcampbell; 02-16-2019 at 09:23 AM.
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Old 02-21-2019, 05:08 PM   #33
Gamil
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I've got a 2011, with AVCS. I'm fairly certain it's the 131.6mm rods. Haven't had a chance to pull the engine and tear it down.

Any idea how different are the STI bearing and rings vs NA? I expect they're stronger, but would they pit with NA rods and pistons?

I've decided to abandon High compression. Probably just Delta 1000 cams and a hybrid intake. Even probably just going to use a stock 253 block b/c it's just not worth the time and money to put NA rods/pistons/bearings/rings into an EJ257 block for SOHC heads
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Old 02-22-2019, 09:36 AM   #34
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Can the 2011 be tuned with rom raider? I am not sure about the bearings or rings. What are your goals, just more power? You can probably add some more timing with 91/93 and pick up some power. Delta cam could be cool.
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