What is an Engine block made of?

Answer 1

The engine block is typically made of cast iron, although in the late 1990s engine blocks made from plastic and other experimental materials were being used in prototype cars with the hope of developing more lightweight, efficient vehicles.

A cast iron engine block can comprise a substantial portion of the weight of the car, and usually requires multiple people to be removed and worked on safely. As the engine block is the heart of the engine, because of the necessity for cooling it means the cylinder blocks are quite complex in shape, and therefore manufactured by casting. When the engine was in the early stages cast iron was used as aluminum was a new material and the process of using alloys was nonexistent. Now we can cast with alloys with good fluidity and small solidification range. The most common modern engine block is cast from an aluminum alloy. Grey cast Alloy is satisfactory in respect of all the properties except density, and is the tradition material for the engine block. A good choice would be flake graphite cast iron to grade 17 in BS1452, giving 262Mpa tensile strength in a standard test bar.

Aluminium alloys have been used for almost 100 years for engine blocks starting, not surprisingly, with aero engines and racing engines. They normally required a cast iron or cast steel cylinder liner but since the 1990s localised aluminium silicates have been used to impregnate the aluminium at the cylinder running surfaces. The resulting surface is said to have almost ideal tribological characteristics (when paired with the right piston ring material). Audi even uses this system on its high performance diesels, with their very high firing pressures.