Keep in mind that moment of area goes up with the cube of the height and only increases linearly with thickness. Steel pistons with thin tall ribs are just as light and stiff as aluminium pistons.Tommy Cookers wrote: ↑11 Feb 2019, 22:55steel is 3 times the density of aluminium alloy
(and a steel piston 33% as thick as an alloy piston won't be stiff enough to behave properly)
but 'fortunately' for the steel piston the engines are limited to about 12000 rpm - so they can stand steel's extra weight
Also, steel's young modulus is roughly 3 times that of aluminium so any steel feature of the piston subjected to uniaxial loading can be just as stiff as aluminium for the same mass.