like the title says,im wanting to know what heads will swap with what...am i right in thinking all sohc heads will swap with all other sohc heads and that its the same with dohc heads...but that sohc and dohc won't interchange with each other.

 

i more interested in sohc stuff but it would be nice to know if i could slot sohc heads on a dohc block, as the dohc blocks a way easy'r to get hold of

subaru's are like legos. you can interchange just about everything. all sohc heads can interchange with each other, and all dohc heads can interchange with each other, you can even swap a sohc setup for a dohc setup. every single one of the ej motors is the same block, just different amounts of bore and stroke make up the larger motors...

Before anyone says anything will swap with anything.....what year/model engine do you have, and what are you looking to swap.

 

Whether the engine is n/a or turbo brings in complexities, as well as what phase it is, exhaust port (single or dual port), intake manifold fitment, etc.

You'll need to be concerned with the resulting compression ratio because the larger displacement motors have greater combustion chamber volume.

 

I think that if you swap a set of 2.5 heads onto a 2.2 you'll drop the compression and up the flow - great for a F/I buildup, but not good for a N/A buildup.