Forged pistons, everything you need to know

If you like cars, you probably know that many performance builds use forged pistons, but do you know why? Recently, research has been carried out into the different metallurgical properties of cast and forged pistons. What is the difference and what do you gain? We’ll tell you.

First of all, the most important thing is to understand the differences in the processes behind the names. Casting a piston is simply melting a metal alloy, pouring it into a mould and letting it solidify. It is a simple and economical concept because it is easy to do again and again. For this reason, casting is popular for production models, as it means they can produce many parts. It also offers some design benefits, giving the manufacturer a great deal of freedom to determine the alloy recipe and the shape of the part.

Forged pistons, are they really stronger than cast ones?

However, while the liquid is in the mould, there is a certain lack of control over how the metal forms. If you look at the crystals inside a cast piston, you can see that there is little uniformity. Air pockets can sometimes form. This means that a cast piston is weaker than a forged one, even if they are made from the same material.

There are also so-called “billet” pistons. This type is formed from a larger piece of metal, which is then cut and shaped to the desired form. The internal crystals of the metal are dense and have a fairly uniform size. When it is cut, a weak point can occur where the grain of the metal meets.

For their part, forged pistons are manufactured in a similar way to the above, but instead of being cut, they are heated, placed in a forge and pressed with great force. This causes the crystals to form a tight, aligned grain. Once this is achieved, the piston has far fewer “empty” points, so a much stronger and more resistant part is produced. In other words, the forged piston better withstands the “abuse” of the most demanding engines.

You’re surely left with many questions, which is why we’re going to look at this video that shows the manufacturing processes in much more detail. That way you can learn the difference between the different types of pistons. Which one will you choose?

https://youtu.be/rK0l68zwZOg