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Guest Message by DevFuse
 

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EJ25 DOHC heads on SOHC block?


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10 replies to this topic

#1 RallyKeith

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Posted 20 April 2006 - 03:18 PM

So, I might be able to get a cheap short block from a 99RS, but I think that means it's a SOHC. Can I put my DOHC heads on it with out any problems, and will it bolt in place of a 96-98 IE Plumbing for PCV?

Keith

#2 cookie

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Posted 20 April 2006 - 03:36 PM

I trust you mean 2.5? The later DOHC 2.5s had the same block as the SOHCs and replacement of the early ones is with the later.

#3 RallyKeith

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Posted 20 April 2006 - 03:43 PM

I trust you mean 2.5? The later DOHC 2.5s had the same block as the SOHCs and replacement of the early ones is with the later.


Sorry, I thought I put that in the title. EJ25

What do you mean that replacement of the early one is with the later?

#4 cookie

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Posted 20 April 2006 - 03:46 PM

I understand the dealer only stocks one normal compression 2.5 block. The later one replaces the earlier one. At one point I was considering buying a 98 Forester with a bad engine, that's what the dealer told me at the time.

#5 TheYeti

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Posted 20 April 2006 - 04:06 PM

The 99 block will work with your heads.

#6 ballitch

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Posted 20 April 2006 - 09:42 PM

yeti is right, you can use the newer SOHC block under your DOHC heads, direct drop in. however you will take a small lowering in CR by doing this. if i were you i would look into getting a whole SOHC motor and replacing your DOHC heads.


~Josh~

#7 TheYeti

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Posted 21 April 2006 - 07:58 AM

Aren't the piston heads about 1mm shallower on the phase II's? That would bump the CR slightly when using the DOHC heads, wouldn't it?

#8 Storm

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Posted 01 May 2006 - 12:28 AM

Aren't the piston heads about 1mm shallower on the phase II's? That would bump the CR slightly when using the DOHC heads, wouldn't it?

Yes. You'll take a CR hit when you put SOHC heads on a phase I block. The DOHC combustion chambers are about 2cc smaller than SOHC heads.

The only Issue I see with putting the DOHC heads on the phase II block is the need for the correct intake manifold since the bolt pattern is different.

Other than that....it's legos for everyone!

Jay Storm

#9 Gnuman

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Posted 01 May 2006 - 02:13 AM

Yes. You'll take a CR hit when you put SOHC heads on a phase I block. The DOHC combustion chambers are about 2cc smaller than SOHC heads.

The only Issue I see with putting the DOHC heads on the phase II block is the need for the correct intake manifold since the bolt pattern is different.

Other than that....it's legos for everyone!

Jay Storm


Ummm, the intake manifold bolts up to the heads, not the block.

#10 970subaru

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Posted 01 May 2006 - 02:25 AM

I think thats what he was saying.

#11 Storm

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Posted 01 May 2006 - 09:55 AM

:clap:

I think thats what he was saying.

;)




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