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Old 06-29-2018, 10:18 PM   #1
fastlate
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Member#: 446558
Join Date: May 2016
Location: VA
Default Need ej25/22 frankenmotor advice please- old schoolers!

I know most people here might be too hip for this but I'm about to put together a cheap na frankenmotor using ej22 phase 1 heads.

My question is on choosing the ej25 block. I have found that apparently the 1996 ej25d has different pistions than the 1997-99 ej25d and according to wikipedia, " The 1996 EJ25D uses different pistons than what was used for 1997-1999, which will increase the compression ratio significantly if combined with 1997-1999 EJ25D heads."

How much of a difference would using this 96' block vs. the 97-99? I'm going for maximum compression and hp. I've also read that the ej251 could be used, but I have yet to confirm that. (I have one of those already sitting around)

I'd also appreciate any advice on choice of ej22 heads. I have a set with adjustable lifters and shimmed.
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Old 07-21-2018, 03:07 AM   #2
subi400
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Member#: 216984
Join Date: Jul 2009
Chapter/Region: NWIC
Location: Coeur D Alene, ID
Vehicle:
1996 Impreza outback
Green

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It is true that the ej25D pistons from the 96 legacy 2.5 are different than the 97-early 99 ej25d engine.

The best combo that has been come up with is this:

1. 99-2005 ej251 shortblock in good condition
2. ej22 dual port heads like from a 95 legacy with the pad style rockers so you can run the delta 230 hp cams with stock ej251/22 cometic hybrid head gasket
3. obx dual port equal length header
4. Chamber match the heads to the 99.5mm bore of the block
5. run a 98 impreza 2.5 rs ecu or 97-98 legacy ej25d ecu is similar

I had built an ej251/22 head combo with the single port heads at the time with an old school single port borla uel header, chamber matched the ej22 heads and used the hla's rocker assembly and delta 230 hp cams.

I believe what really helped is the head chamber match to the bore of the block and the delta 230 hp cams. I got pretty good gas mileage out of this motor compared to almost everyone else that built one of these.

If you would like to know more, send me a pm. I still have the single port ej22 heads from my hybrid with less than 4k miles on them with the delta 230 camps. pretty mint.

~Josh
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Old 07-24-2018, 11:38 PM   #3
Homemade WRX
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Member#: 33782
Join Date: Mar 2003
Chapter/Region: MAIC
Location: Mooresville, NC
Vehicle:
96 in the garage
search FIRST, then PM!!!

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One thing to note with the EJ25D and the later NA EJ25x engines is rod length changes from the normal 130.5mm

Also the EJ25D was a 48mm rod journal.

But if you're using the full shortblock, and it sounds like you are, those aren't issue.
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Old 08-01-2019, 03:14 PM   #4
Elver231
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Member#: 456773
Join Date: Oct 2016
Chapter/Region: International
Location: Guayaquil, EC
Vehicle:
1995 Legacy
Dark Green

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Quote:
Originally Posted by subi400 View Post
It is true that the ej25D pistons from the 96 legacy 2.5 are different than the 97-early 99 ej25d engine.

The best combo that has been come up with is this:

1. 99-2005 ej251 shortblock in good condition
2. ej22 dual port heads like from a 95 legacy with the pad style rockers so you can run the delta 230 hp cams with stock ej251/22 cometic hybrid head gasket
3. obx dual port equal length header
4. Chamber match the heads to the 99.5mm bore of the block
5. run a 98 impreza 2.5 rs ecu or 97-98 legacy ej25d ecu is similar

I had built an ej251/22 head combo with the single port heads at the time with an old school single port borla uel header, chamber matched the ej22 heads and used the hla's rocker assembly and delta 230 hp cams.

I believe what really helped is the head chamber match to the bore of the block and the delta 230 hp cams. I got pretty good gas mileage out of this motor compared to almost everyone else that built one of these.

If you would like to know more, send me a pm. I still have the single port ej22 heads from my hybrid with less than 4k miles on them with the delta 230 camps. pretty mint.

~Josh
Nice! Do you still have Delta Cams 230 hp? I am interested
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