If you're into building EJ22D's, you need to read this closely, because it matters to you, and only 97-99 EJ25D heads will be used in this equation, as the 1996 EJ25D heads have chambers which are too large for the EJ22 bore, and should never be used in this sort of application.

EJ22D Version 1 - EJ25D heads + EJ22E/1 block (14.5cc pistons) = EJ22D V1: N/A w/ EJ222 headgaskets yields 9.3:1cr, but EJ22T head gasket yields 8:5.1.

EJ22D Version 2 - EJ25D heads + EJ22E/2 block (12cc pistons) = EJ22D V2: N/A w/EJ222 head gaskets yields 9.6:1cr, but EJ22T head gasket yields 8.8:1.

EJ22D Version 3 - EJ25D heads + EJ221/2/3 block (3.5cc pistons) = EJ22D V3: N/A w/EJ222 head gasket yields 10.3:1cr, but EJ22T head gasket yields 9.8:1.

EJ22D Version 4 - EJ25D heads + EJ22T block (28cc pistons) = EJ22D V4: EJ222 head gasket yields 7.8:1cr, but EJ22T head gasket yields 7.4:1cr.

There are only FOUR EJ22D variants that can be achieved with 97-99 EJ25D heads and all of the EJ22 blocks in combination form. All 97-99 heads have a 46.6cc (rounded up to 47) clover chamber, and all EJ22's have a 97mm bore, 75mm stroke. I repeat, do NOT use 1996 EJ25D heads. Those are identified as having "16 Valve Quad Cam" on their valve covers.

A long while back, when I first started building these, I originally based my coding off of what Subaru does to its EJ's to keep the identification easy. Example, if you're using EJ20K heads on an EJ22E block, I would call that combo the EJ22K, since the 5th digit identifies the heads in use. Have fun with this knowledge.

(I am EJ22D, but for some reason, I cannot access my original profile, so I made this one.)