As promised, here's a picture of the original cone air deflector of a porsche 11-blade 245mm fan/alternator combo:
And here's a preliminary air deflector I made to direct more air to the heads and to overcome the barrier of the first cooling fin. This is because the fins on the nikasil 964 cylinders I use are very small (therefore low, so the heads fins stick out a lot). It gave a 50F lower head temp
The 964 cylinders have M6 thread on top of the cylinders, so I could mount to that. Originally on the porsche 964 those holes are for mounting the knock sensor bridge...
The original air deflector/cone did gave slightly lower head temps for 3 and 4, but not as much as I thought they would. Enlarging the area of the cone air deflector did work, but still not enough to my liking compared to the temps of 1 and 2.
Work in progress
Walter