LO 7-3 Identify and explain the purpose and functions of major piston construction features

Aluminum Pistons and Emissions

Aluminum trunk-type pistons were satisfactory for many years and continue to be used today in many engines. However, other disadvantages of aluminum pistons have come to light as manufacturers strive to reduce GHG and noxious engine emissions while increasing engine longevity and horsepower. Because aluminum pistons cannot withstand the high cylinder pressures and temperatures produced by smaller, power-dense engines with increased torque and horsepower, new materials have been sought as replacements. Ceramic-coated pistons and ceramic alloy crowns are among the replacement materials. These pistons not only withstand greater thermal loading but also help reduce heat loss from the combustion chamber. Reducing heat transfer to the coolant or oil means more fuel energy is converted into mechanical energy.