The Iida Family is a prestigious family that has been in heroics for generations.
The Iida family has a long tradition of being heroes since Tenya's grandfather's days. Most of them seem to have the same Engine-type Quirk with exhaust pipes sticking out of them, granting them great speed.
Tenya's grandfather discovered a method that allows them to improve the Engine Quirk, a method that was passed down through generations. It consists of removing the exhaust pipes from the body, which incurs an extreme amount of pain, and then training hard. The process requires patience and perseverance, but new and more powerful pipes will grow in, giving them the ability to run at a higher speed for much longer time.