Aluminum is the material that dominates the construction of the pistons of diesel engines. However, these pistons are approaching their limits in mechanical applications that deliver more effective powers of about 80 kW per liter displacement. The combustion chamber may reach 400 ° C and 200 bars.

" For applications in severe condition, we are now ready to provide steel pistons for diesel motors "Said Rainer Fluhr, board of directors of Kolbenschmidt Pierburg. Indeed, until now the steel piston seemed to be heavy in order to be competitive with aluminum, new developments have allowed to optimize its geometry and make it more competitive.
One of the most critical areas of aluminum piston axis is where it stands very high loads. With the greater strength, a steel piston can reduce the quantity of material in this area and the axis can also be shorter. Ultimately, the difference in mass between the two types of piston can be reduced. Another plus, for the same thermal expansion of cast iron engine block, steel piston reduces the tolerances and the preload segments on the cylinder wall. The advance OEM  accordingly improved sealing and reduced friction.