Now that I've pulled apart a 2.8, 3.0, and 3.2 M104 I've got a few questions to ask about these heads...

The biggest one is, which cylinder head design flows best? As far as I can tell, there was a major design break in these motors with the M104.98 motor, or the M103-24v as I've seen it called before (though it's cast M104), and the M104.94/.99 series of heads. The exhaust is the same on both head designs, the manifolds have the same flange etc., but that's about where the similarity ends.

Cue pics...
This is the late model head, that came out of a late W124 chassis car. The water port is on the front of the head and there is a slider on the intake side of the chain drive, not a roller.

Pay no attention to the datsun head below it, that was for something else.

Now this is the M104.980 head that I got when I pulled the motor out of a 1990 300CE-24. If you notice, the way the intake manifold mounts is much different as is the overall intake port design.

Another interesting thing to note is that the valves are less visable on this engine as the angle cut on the intake mounting flange is actually opposite the angle cut on the later M104 head. That is to say, that this head was designed so that when the engine is mounted in the car at its 15 degree lean over, the intake mating surface is exactly vertical while the later model head has a pronounced angle to it, making the efi intake mount at a much more radical upward angle (if that makes sense.)

Also, on this early model head, it has a tensioner sprocket located right below the intake cam, and the water outlet is directly on the side of the block, in the same location as the M103 water outlet (which I'm pretty sure is why it's there).


Vs...again, don't pay attention to the datsun block it's sitting on...


So the question is, which head flows better? Before anyone gets carried away with CIS vs EFI or displacement, lets talk about head design. The car it's going in is very light unless I can find a 190 2.6 with a blown motor/no drive train so I can stuff it in that and even with the most radical cams possible (which will at some point happen, just not at the beginning) the motor will have enough torque for anything I'd like to do. Also either way the engine will be running MS3 so again, induction system will be pointless. At this moment let's just discuss head and engine design.