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Old 09-09-2010, 10:35 PM   #1
Scooby Newbie
Member#: 193455
Join Date: Nov 2008
Chapter/Region: South East
Location: Charlotte, NC
Default Hybrid build options

I recently bought an 04 wagon that threw a rod. I contemplated rebuilding the 2.0l with forged rods and pistons but then decided against building an open deck motor. Since I also have a budget in mind I've been leaning towards building a hybrid motor. Theres an ej257 shortblock that I'm looking at that spun a rod bearing. I'm wondering how reliable the bottom end would be if I rebuilt the block with acl rod and main bearings, eagle rods, and OEM sti pistons, then pairing it up with the ej205 heads off of the original motor. The reason I'd rather run oem pistons than aftermarket is because I'd want to use the oem tight clearances.

My goal for this motor is to run around 350 whp reliably for the next 5 or 6 years
So.. to sum up, here are my questions..

How well do the cast oem sti pistons hold up to that kind of power? would it be reliable?

How much would the ej205 heads limit the motor compared to a set of ej255 or even better... ej257 heads?

If I decided to get a set of ej257 heads (and practically build an sti longblock) could I sill use the stock ecu on the 04 wrx?, or would I have to shell out more money for an sti ecu.

I'd appreciate any constructive input

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Old 09-09-2010, 11:07 PM   #2
Ds baruuuuu
Scooby Specialist
Member#: 4724
Join Date: Mar 2001
Location: in my rs with the ej20 love!!
01 01RS


the sti pistons are hit and miss, ive seen some crack on stage 2 power and some last with 350, all depends on the tune.

205 heads will be fine for the 350hp goal, depending on the octane gas you have you might get some knock with that setup because of the compression bump with the 205 heads on 255/257 block.

check out this thread for some good info on it http://forums.nasioc.com/forums/show....php?t=1942615
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Old 09-09-2010, 11:08 PM   #3
Ds baruuuuu
Scooby Specialist
Member#: 4724
Join Date: Mar 2001
Location: in my rs with the ej20 love!!
01 01RS


and if you used the 257 long block you would need to use the ecu but also need to rewire for it (the plugs are not the same)
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Old 09-10-2010, 12:44 AM   #4
Scooby Guru
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
2002 WRX
Hybrid VF22


I would definitely not put OEM STI pistons in. Go straight to forged. There is no reason not to.
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