actaully the b20b pistons are 84mm not 85mm.. remember though, that when you bore out to 84mm on a b18c, you WILL need to resleeve or get golden eagles or something. if you do spend $750 on golden eagle.. why would you use stock b20b pistons? the compression will not be as high as you'd like (10.0:1 give or take a few points.) of you spend the money on sleeving why not just buy new forged pistons? the extra $500 would be worth it.
the only reason i woudl run stock pistons woudl be because of clearance issues. stock pistons can run alot tighter clearances, and therefore have a slight bit more power then a forged piston, but you should more then make up for it with the added compression. besides forged pistons do expand, therefore the clearances aren't that bad once the motor gets working.
general rule 1: any model with an R ending in the name (except for SiR, since an SiR IS an Si) means that the pistons can fit on the rods between models...eg. ITR piston can fit on a GSR rod. GSR piston can fit on a CTR rod. The rods can fit on the respective R cranks.
general rule 2: any engine without an R in the name can have their pistons, rods, cranks swapped between them with minor clearance adjustments to clear the crank in the block. SO for example, an LS rod can accept a Civic Si piston or B20 piston.
general rule 3: you cannot swap between rods and cranks from an R group to a non-R group. The big end of the rod have different sizes when they attach to the crank. For pistons, to get an R group piston onto an non-R group rod, you must mill the small end of the nonR group rod by 0.7mm one either side.
Now if you guys bothered to read my Engine Package II Article you would have known that and I wouldn't have retype the damn thing again for you!! SO PAAAHHHHLEEEEZE READ THE f**kING ARTICLES WILL YA???!!! LOL
BTW if it were me? if the rod was milled to have everything fit, I would shotpeen the rod to restore the surface tension and regain the strength on the rod...but that's just me....you can do whatever you want...
I was going with the JE forged pistons in the 85mm bore.
the CR of the piston is 10.5:1.
MD: i did read the articles, i just had a few questions.
I know the ls or b20 rod is wider at the small end than the b18c's, i wanted to make sure i didn't have to much room between the rod and piston.
piston rock prevents ring sealing and creates a lot of noise. Arias pistons are notorious for having too much play at the piston to wall clearance on cold starts. You can be off by as little as 0.0003 in. on piston to wall and run into some compression issues. So I can't imagine what happens when the pin clearance is off by 0.7 mm or 0.028 in. on either side of the pin and how much extreme play that creates. Secondly you choose free floating bushing pins for a reason...to avoid play at the level of 0.0001 in.
However, if you want to try and see how long your engine lasts with "that much play", please be my guest. I'm not one to obstruct a firsthand "learning" experience...pop a set of B20 pistons on an "R"-group rod, balance the pistons and rods first, and run the recommended piston to wall clearance...see what you get when you fire up the engine....