Ej20 pistons
 

Does anybody know if ej20 pistons are sided?
If so are there any identifing marks? Other than the a & b size marks?

OEM are from a 1995 WRX.

Attachment 67426

Attachment 67427

Kind of yes, some were clearly identified as in the pics above L & R but in general they have two marks on them. The first will be bore size. Which are size A or Size B, the top of the block has a stamp on it and will have either an A or a B for each cylinder. Obviously this is irrelievent for after market pistons and engines that have been rebored.

The second mark will be a small circle this indicates the offset direction and these circles should be closest to the front of the engine when installing the pistons. So techically you could put a right hand piston in a left hand bore providing the circle was nearest the front of the engine.

Some have arrows, in which case these should be pointing to the front. In this instance the arrows are at the top on one side and are at the bottom on the other but they all face the front of the engine.

I got a JDM EJ20X from 06 LEGACY GT, one of the pistons is broken and when I take apart the engine, I realize there are 3 pistons marked "B" and only one marked "A"
anyone could help on this ? I mean if there are 2 pistons marked A and 2 marked B, wouldn't that be more reasonable?
https://cimg3.ibsrv.net/gimg/www.sco...e61e9d52ea.jpganother is broken with B markhttps://cimg6.ibsrv.net/gimg/www.sco...457ce98607.jpg

As previously mentioned the A & B refer to the fitting tolerance of OEM pistons and is shown stamped on the block.
https://cdn.shopify.com/s/files/1/11...G?v=1459904544