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Frank, I think there is a lot of sense in using cast iron. My ancient tech 97 Ranger with a cast iron block and head does very well for mileage, with only two valves per cylinder.
In the ecoboost.
Exhaust manifold integral with cylinder head, impossible with aluminum. Significantly faster warm up times, less complexity and no potential manifold gasket failure.
Iron absorbs heat much more slowly than aluminum and iron blocks and heads have basically identical expansion characteristics, with much less stress on the head gasket.
Maybe in a future design they will go back 60+ years and eliminate the head gasket altogether.
The weight penalty, vs AL, is not as great with precision thin wall iron casting controlled by computers. The 3 cyl ecoboost engine block is about the same size as a sheet of typewriter paper.
regards
Mech
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