For starters, the intake valves on the NA engine are bigger than the ones of the turbo. I measured them and the turbo are 1 3/16" while the NA ones are 1 1/4" Furthermore the turbo ones are marked IN1 while the NA ones are marked IN2. The exhaust valves are identical at 1 3/32"
As is already known, the valve covers are different, with an oil return bung on them. But what I hadn't noticed before is that the passenger side turbo head has a coolant return line sticking out of the side of the head. This is not present on the NA head.
Next, I looked at the faces of the heads and compared them and the gaskets. The NA head has more coolant passages in the head on the intake side.
You can see from my old turbo head picture what I am talking about. On the right there are three, but on the left there are only two. On the NA there are three slightly smaller passages on the intake side.
Sorry, i don't have any new pics to help show all this. I am gonna try and borrow a camera in the next day or two and give more blow by blow of the differences I have found.
When I disassmbled the heads, the rockers were identical between the two, with identical markings on them. And as is known, the cams are a very different grind. I don't know how to measure the lobes for lift and duration but can describe what I saw. The NA cams have the intake and exhaust lobes about 180 degrees apart on the rotation. The turbo cam has them more like 40 degrees apart. There is a huge difference in the grind between the two.
The manifolds are definitely identical, as are intake and exhaust port sizes on the heads themselves.
Lastly, the turbo head is cross hatched just like the EJ22T blocks are. This makes me wonder if it is made using the medium-pressure casting technique Xephyr talks about being used for the turbo block itself. The NA head doesn't have the cross hatches, and in addition to not having the coolant bung(that appears to be drilled in and added after casting, while the NA heads don't even have a spot where this is possible.) there are a few other subtle differences in braces and what-not that make me sure the heads are different cores. I will post pics of differences as soon as I can.
Lastly, just a side not about the block itself. Here is a picture of the new EJ257 STi block.
You will note how skinny the braces are on the crankshaft axis. The 'semi-closed" braces on the sides are much much thicker. I was quite surprised, but the NA EJ22 deck had much larger braces on the crankshaft axis than the EJ257. They were about as thick as the side braces on the EJ257! Even though it is still an open deck engine, this makes me want to further pursue my frankensubby project as a turbo build. I have been talking about these old NA blocks being stronger than people give them credit for, and we all know the USDM EJ205 blocks are open deck.
Here's an EJ205, and my EJ22NA block has pretty much identical bracing to this... Now I really need to figure out if I want to do this with some EJ25 heads and stock NA pistons OR make a truly EJ22 build and use the NA heads with turbo cams on the NAEJ22 block with EJ22T pistons. If someone has a set of used, but functioning EJ22T pistons they wanna donate to the cause or sell super cheap, let me know and it will make up my mind. I can get a new set from Quirt Crawford for $100, so used ones better be real cheap.
More to come...
Wait a minute, I can call LegacyMax and have him check for me. He works for CCR building EJ22's all day long...