Last weekend, drivers and both needed some serious powertrain overhauls, which included both the MGU-H and MGU-K systems. If that sounds like nothing but a jumble of letters to you, then you’re not alone — and that’s why today, we’re looking into what both of these systems do.

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In a Nutshell

To put this as simply as possible, both the MGU-H and the MGU-K are part of a modern F1 hybrid: the otor enerator nit - eat, and the otor enerator nit - inetic, respectively. They’re two components of the energy recovery system (ERS) and an evolution of the previous kinetic energy recovery system (KERS) that was introduced in 2009.

Now, let’s get into details.

Motor Generator Unit - Heat (MGU-H)

In a sentence, the MGU-H harvests thermal energy from an F1 car’s exhaust and is an evolved part of a turbocharger. A turbo consists of two parts: a turbine and a compressor that are joined by a shaft. The turbine is connected to the car’s exhaust, and the compressor is connected to the intake. The exhaust gases cause the turbine to spin, which in turn spins the compressor, which then sucks in air and compresses it before sending it down the intake. The system altogether creates a more efficient way to get a lot of air into an engine at once, so that engine can burn fuel more quickly and increase power.

The MGU-H is popped right in between the turbine and the compressor. Like a regular turbo, the MGU-H also harvests exhaust gas. What’s different here, though, is that the MGU-H is made up of magnets that spin around when it’s filled with exhaust gas. Those magnets generate electrical energy, which is then sent to, essentially a battery, ready to be used when need be.

All that being said, the MGU-H also acts as a motor in certain instances.

If you know your turbos, you know of the phenomenon called “turbo lag.” Typically, when you step on the accelerator, the turbine takes a second or two to spin up and respond to your direct throttle input. The MGU-H steps in, taking on a motor-like role to eliminate turbo lag by providing power in those lull moments.

The MGU-K is an evolution of the original KERS unit, and it’s pretty similar to the MGU-H. Instead of being attached to the turbo, the MGU-K is attached to the crankshaft. When a driver presses the accelerator, the MGU-K becomes a little motor that adds its own power on top of the engine’s power. When activated, it adds about 161 horsepower to the car’s total output, but it can only be activated for brief moments of time.

If a driver opts to slow down, though, the MGU-Kgenerates energy. It, too, is made up of spinning magnets like the MGU-H, but here those magnets are used by the MGU-K to harvest the kinetic energy in the crankshaft. This helps drivers slow down more quickly thanks to the added resistance, and additionally adds energy to the car’s batteries.

The Power Unit

As mentioned before, the MGU-H and MGU-K form the energy recovery system of an F1 hybrid engine. The ERS is also half of the power unit, with the other part being the combustion engine. In a hybrid system, both combustion and electricity work together to create the power that’s deployed on the race track.

Looking to the Future

As you can imagine, all these spinning magnets can get expensive. So, as part of F1's growing effort to reduce the costs of competition, the MGU-H will be no more in F1's 2026 new power unit regulations. The MGU-H is specifically very costly to develop. As for the MGU-K, it can remain, as current regulations limit the amount of power that the system can recover.

As the World Motor Sport Council put it, the goal is to open the doors to “newcomers” to “make it possible for them to join the sport at a competitive level.” After all, most automakers don’t use the MGU-H on road cars, so developing one for racing purposes doesn’t make a ton of sense. Meanwhile, the principles derived from the MGU-K are incredibly relevant to battery regeneration for electric and hybrid vehicles.