Basically the same as before; added guides to the port loft, so it's not straight through. Offset the cylinder banks, and closed the block ends. Redid the crankshaft for more realistic journals and squared the bore x stroke at 6cm for 2liter displacement. Getting faster, at least.
My assumption was the X-16 was too narrow angle 45* to be practical, but it's perfectly sensible looking.
Set to 3/4 (bore x stroke) it's 2 liters, offering apples to apples comparison to X-12. 1.5L X-12 to come, but I like the squared bore with the 60* angle.
Not sure if I mentioned this before, but exhaust gas will go toward the horizontal with outlets on each side. Breathing will come from the four corners so to speak. I don't really expect any very interesting differences between these two.
The 16 will be about 3 inches longer. Will use the same pistons, architecture and materials. Weight fairly similar, fuel consumption...