I understand that the B18C5, B18C1 and B16A2 internals are interchangeable, but what about the B16A1. Can u for example change up the pistons, cams, springs, etc with the ITR counterparts w/ no probs (sans pistons for the milling part)?

 

The cams and springs will fit, but the pistons won't.

 

all of those parts you have listed are interchangeable among ANY b series motor with an 81mm bore, and the valvetrain stuff is interchangable with ANY b series vtec head.

 

So regardless of OBD0, I, or II, etc they are all interchangeable.

When u say 81mm bore, is that stock spec on B16A1?

 

You can't use the type R rods though.

 

yes, the engine does not care what the obd is.

 

i just pout a type r manifold on my ls head and just installed b16 pistons into my ls. The fit just as good as the stock ones and my compresiion just went up a bit as well.

 

type r manifold doesnt fit on LS. B16 and B18A/B have different intake manifold bolt patterns. I know this for a fact. Maybe you are thinking of a skunk2 manifold for LS.

 

CTR pistons work with a b16a if u mill the rods gives u about 11.1:1 compression a

 

CTR pistons and ITR pistons both need milling of .1 mm on the rods I believe. Looking strictly at USDM ITR vs JDM CTR on a B16A1, what will the compression yield with the two?