engine block
 

Is the block iron or alloy? I have read both ---- The mercedes website says that it is alloy.

The cylinder heads in the AMG 4.0-litre, V8 biturbo engine are made of a zirconium alloy.

http://media.daimler.com/dcmedia/0-9...8-0-0-0-0.html

The link above indicates that the cylinder bores are treated with the same process as used on the 6.2L M156 bores. Here's a generic explanation of the process used to spray-on the (iron) liner - pretty cool IMO:

"Plasma spray is the most versatile of the thermal spray processes. Plasma is capable of spraying all materials that are considered sprayable. In plasma spray devices, an arc is formed in between two electrodes in a plasma forming gas, which usually consists of either argon/hydrogen or argon/helium. As the plasma gas is heated by the arc, it expands and is accelerated through a shaped nozzle, creating velocities up to MACH 2. Temperatures in the arc zone approach 36,000°F (20,000°K). Temperatures in the plasma jet are still 18,000°F (10,000°K) several centimeters form the exit of the nozzle."