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EJ25 DOHC heads on SOHC block?

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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

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.

  • Author
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?

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.

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~

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?

  • 2 weeks later...
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

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.

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