Engine

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

Description
Engine grants both Tenya and Tensei engine-like protrusions that allow them to move at extraordinary speeds.

Thanks to Engine, Tenya and Tensei can both dash through long distances in a short amount of time. This makes them suited for missions that involve reaching a far away place as fast as possible, chasing after an object moving at high speeds or even escaping from an overwhelming threat.

Engine appears to require fuel in order to work properly, similar to an actual vehicle. In Tenya's case, he drinks orange juice as a source of fuel for his Quirk, while carbonated drinks make him stall. Tensei appears to favor grape juice instead. If they don't refill themselves, their Quirk will gradually lose potency until it stops functioning altogether.

The two Ida brothers have access to Recipro Burst, a super move that grants them a short-timed, yet immense burst of speed. This move overheats their engines, forcing them to undergo a cool down period right after performing it.

Tenya's Usage
Tenya's Quirk manifests around his calves.

Those engines give Tenya massive leg strength when activated, allowing for increased kicking power. Consequently, Tenya's fighting style ends up revolving around fast and powerful kicks, which are strong enough to crush even metal.

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.

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.

Because his engines are located in his upper body, Tensei is capable of boosting himself vertically, allowing him to acrobatically climb up walls as well as hover slightly. Despite this, Tensei is perfectly capable of propelling himself forward, covering long horizontal distances as well just like his younger brother. It's unknown if he has to change between gears like Tenya.

However, Tensei has noted that he can't make tight turns properly when at high speeds, meaning that he has to slow down in order to do so. Also, if he crashes into walls while at top speed, it can result in him seriously injuring himself. As such, he has airbags installed into his costume for safety.

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.