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Guest Message by DevFuse

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EJ25 DOHC Heads on SOHC block?

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4 replies to this topic

#1 [HTi]Johnson


    Head Trauma, inc.

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  • Coburg, Or.

Posted 23 May 2007 - 02:30 PM

Hello. I was wondering if the DOHC heads off my outback will fit a 2.5 block that originally was SOHC? Thanks for your time.

#2 ShawnW


    Subaru Master Technician

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  • Denver, Colorado

Posted 24 May 2007 - 10:03 PM

Yes. Direct swap no problem.



    Elite Master of the Subaru

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  • Tazewell Virginia

Posted 24 May 2007 - 10:07 PM

I think the combustion chamber is smaller on the dohc, so you'd have somewhat higher compression ratio after the swap.

#4 ShawnW


    Subaru Master Technician

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  • Denver, Colorado

Posted 24 May 2007 - 11:57 PM

Nope just a difference in the pistons themselves but compatible all the same. SOHC pistons are higher compression.

#5 Aspen


    USMB Regular

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  • Ontario

Posted 25 May 2007 - 12:39 PM

Your new compression ratio will depend on the gasket you use. I suggest a cometic 60 thousands. Should be around 10.6:1. should be good on 89 octane.

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