ej25d vs ej251 internal diffrences (not dohc v sohc)

A

abenson100

New member
im wondering about the rotating assembly. I have heard there is a difference in the pistons. I am thinking about using (or going to) ej25d short block with my ej251 heads this way I don't need to re wire and such.

 
ej25d have 9.7 to 1 comp ratio vs the 251 10. something to one and the difference is in the pistons . on the blocks that I have seen at least.

 
the piston dish is different between the two engines and if you put 251 heads on a D bock u have to run the D HG or you will run the pistons into the head as they rise above the block a bit.

 
Ive done one of these setups recently. As stated you have to use the 25D head gasket. This makes things not line up as well, but its not that big of a deal. There are internal differences as well, I forget exactly what but something about thrust bearings in different positions. I think that the EJ251 crank has more counter balances as well.

 
Sorry to raise an old topic. I want to do one of these setups too: EJ25D short block in an EJ251 car. The 25D has a knock I will have to repair, so I want to buy a full gasket kit. Would it work to just buy the EJ251 gasket kit and EJ25D head gaskets? I don't know if the 25D and 251 short blocks are similar enough that this would work. Thanks!

 
If I were going to do it again Id have some gaskets made from Cometic at about a .8 or 1 mm thickness.  The EJ25D gasket is unnecessarily thick imo.  It's about 1.5mm vs a .5mm which is the SOHC thickness.  The pistons dont clear the block by very much, and not nearly as much as the thickness difference in hgs.  As for your question the answer is yes. 

 
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