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Old 05-11-2022, 06:08 PM   #1
brodio123
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Default EJ20 vs EJ25 heads

currently putting a ej20 in my car as a temporary solution until i can get a iag shortblock. Later down the road am I able to put the heads from the EJ20 on a EJ25 built shortblock? not sure if theyre plug and play for each other or not. thank you
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Old 05-11-2022, 06:27 PM   #2
benflynn
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Not really, you can open the chamber, but then ej20 heads have their own issues
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Old 05-11-2022, 06:46 PM   #3
Haevn
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where are the heads from the old motor that your taking out?
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Old 05-11-2022, 09:51 PM   #4
SuperPete
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depending on the heads you can change your compression rate and be dealing with bunch of issues. Stick on OEM, you will not gain anything from 205 heads unless they are from 207
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Old 05-12-2022, 07:12 AM   #5
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Its not a plug and play issue, Subarus are like Legos, everything will plug....its the play that is often not apparent.

2.0 heads on a 2.5 is known as a hybrid and is a thing. Here are the ways to do it:

1. Have your 2.0 heads machined to the correct compression ratio. Expensive.
2. Get JE FSR hybrid pistons when, due to their design, are the correct compression ration with 2.0 heads. Easy.
3. Stack some head gaskets to get close to the compression ratio. As good of an idea as invading Russia in winter.

I chose option 2. I make 2.5 power. I get 2.0 gas mileage.
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