Can't say I've ever heard of a cammed piston. That was a fun read. I wonder if it just isn't used anymore because most applications now use forged aluminum and very short skirts. I haven't heard of pistons heating up non-symmetrically that would warrant that shape.
I wrote my diploma thesis in an industry research group trying to figure out the optimal (non-cylindrical) shape of the cylinder bore.
We attempted to model static stresses from mounting the cylinder head, thermal stresses, and mechanical stresses from mass forces, combustion forces and the like.
Our goal was to achieve low combustion gas blow-by, low oil ingress into the combustion chamber, yet low friction between piston and cylinder wall.
We used simulations (about three months worth IIRC) and measurements to generate data points for a continuous ersatz model of the physical phenomena, then performed multi-criteria optimisation on that model. The resulting shape was interesting, but not exactly earth-shattering. Kinda randomly warped.
This work was tremendous fun, and I learned a lot.
Top image is the cylinder shape without optimisation, bottom is the optimised shape.
Obviously, the contour distortion is massively exaggerated (ISTR a factor of 1000), otherwise it wouldn't have been visible; we're talking micron scale here.
I think nothing in the article is actually obsolete. Possible though that using modern computer aided design allows for better control of how the piston expands.
Thermal mechanical stuff is a big pain. One of my professors mentioned as a young engineer measuring expansion on exhaust manifolds by drawing faint scratches and microscope to measure how far they stretched as the manifold got hot. Important because localized thermally induced stress causes fatigue cracking.
I'd be surprised if they don't take asymmetrical heating into account when designing pistons of today, the oil cool the piston from below, and combustion heat it from above. But I can imagine that the effect is less, because emission regulations have been driving down combustion temperatures.
Bulk material is the water jacket temperatures. Those were the old days of 160F coolant temps as per the somewhat amusing artwork. My modern car has pressurized coolant and the thermostat doesn't even start to open until 180F. You are correct about combustion temps, but bulk materials like the cylinder walls and pistons run much cooler than combustion temps, yet bulk material temps generally only increase over time.
Most applications use hypereutectic pistons. They run better cold than forged but can't take the punishment of detonation as well. Skirt dimensions have to do with rod stroke and bore specs, you don't want too much side load on the cylinder wall nor do you want too much weight.
