As usual, the implication that the n52 is inferior is not based upon fact. A few minutes with google will show you that the tensile yield strength of magnesium alloys are 135-285MPa. I don't know what aluminum alloy BMW uses but I looked up 6061 and it is 125MPa. That is annealed but I do not believe you can hold a temper in 6061 at operating temperatures of an engine. At worst, they are similar in yield. I think as applied the magnesium is stronger. It is important to apply the magnesium as BMW did, however and keep it exposed to the coolant temperature, not the combustion chamber temperature. The yield strength of magnesium alloys falls off more quickly with temperature.
The advantage in density is not 30% it is 50%. Magnesium is 1.8g/cm3 and aluminum is 2.7 g/cm3.
The composite block of the n52 is not inferior to an all aluminum block, it is superior. The magnesium adds strength at less weight.
128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport
Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09