Engine

Engine (エンジン) is a Quirk used by Tenya Iida and Tensei Iida.

Tenya's Usage
Tenya's Quirk grants him high running speed through engine-like protrusions manifested around his calves, which he can activate at will.

Through his amazing speed, Tenya can easily travel through large distances and overwhelm foes, as very few people can react or catch up to him. Those engines also give Tenya massive leg strength, allowing for increased kicking power. Consequently, Tenya's fighting style ends up revolving around kicks.

His engines are fueled by orange juice, while carbonated drinks make them malfunction. Furthermore, he can adapt to the situation at hand by switching between gears. There are at least three confirmed gear settings, but he needs to go through each one in proper order as he accelerates further. Tenya once observed that he could only switch up to third gear for a 50-meter dash, implying he needs more distance to achieve his maximum speed.

Jamming the mufflers of the leg engines will cause them to stall. The same thing will happen once he activates his Recipro Burst move, as a trade-off for a short-timed, but immense burst of speed.

Named Super Moves

 * Recipro Burst (レシプロバースト): This move allows Tenya to forcibly accelerate his Quirk, greatly enhancing his speed for 10 seconds but at the cost of disabling his engines for a short period of time. Even Shoto Todoroki could not fully evade Recipro Burst and admits that he expected no less of its incredible speed.
 * Recipro Extend (レシプロエクステンド): After Tenya manages to cool down the negative effects of Recipro Burst, he regains even more acceleration than before.

Tensei's Usage
Tensei's Quirk gives him two exhaust-like engines at the end of his elbows, which he is able to use to propel himself and increase his speed at a rapid rate. He is capable of getting to very high speeds, fast enough to keep up with other Speed-Enhancement type Quirk users, and with cars.

However, Tensei has noted that his Quirk makes him very bad at making tight turns, needing him to slow down before he can reactivate his Quirk. Also, he does not have any brakes, meaning that if he crashes into walls while at top speed, it can result in him seriously injuring himself. He also needs to drink some sort of gas like drink (or even juice) to keep his quirk going like a car.

Named Super Moves

 * Recipro Burst (レシプロバースト): By over torquing his engines, Tensei is able to produce an explosive burst of speed. This also causes his engines to overheat.
 * Rocket Charge (ロケットチャージ): Tensei's hero costume increases and focuses his engines' output, affording him greater acceleration and launching him into the air, like a rocket. This causes his engines to stall.

Trivia

 * This Quirk is similar to Jet, as both grant the user propulsion devices in their lower bodies that provide enhanced speed. The main difference is that in Jet they are located at the bottoms of feet and provide enhanced jumping, while in Engine they are located in the lower leg and provide enhanced running.