* Cast Iron: This is the traditional material for cylinder blocks, known for its strength, durability, and heat resistance. It's also relatively inexpensive.

* Aluminum: More modern engines often use aluminum blocks because they are significantly lighter than cast iron, which improves fuel efficiency. Aluminum is also better at dissipating heat.

While these are the most common, other metals like magnesium are sometimes used in specific applications, but they are less common than cast iron and aluminum.