F1 2021

The RA621H

In 2021, Red Bull Racing and Scuderia AlphaTauri were powered by Honda's challenger power unit, the RA621H. It helped power Max Verstappen to the Drivers' World Championship.

The RA621H

Every year since the World Championship began in 1950, up to the end of 2013, Formula 1 cars have been powered by internal combustion engines, essentially the same motive power as used in the majority of road cars. However, since 2014 and reflecting a move away from fossil fuels, Formula 1 has mixed the power of a petrol driven Internal Combustion Engine (ICE) with Energy Recovery Systems (ERS) resulting in what is a hybrid Power Unit (PU.) Massively powerful and highly efficient it truly is the heart and soul of a modern-day Formula 1 racing car.

The Advanced Hybrid Electrical Systems ingeniously recycle energy produced by the brakes and exhaust gases. Optimising power through these advanced efficiencies creates solutions that drive innovation from the race circuit right through to the Honda road car range. Take a look at the individual elements - and the crucial roles they play to make up the modern day power unit - below.


Every race starts here. Current regulations specify a 1600cc 6 cylinder engine with the cylinders split into two banks of 3, aligned in a V shape. The fuel used is strictly regulated and is essentially similar to that bought at the pumps for road cars.


The current internal combustion engines also use a turbocharger so that apart from the electrical power boosting the engine from the hybrid system, further power comes from the turbo, which works by taking the hot gases from the engine’s exhaust system and uses them to spin a compressor that increases the air and fuel mix going into the engine. Burning fuel needs oxygen - and burning fuel efficiently needs even more, especially when restricted to 110kg of fuel per race. Our turbo charger simply helps the engine ‘breathe’ faster - handy when it spins at roughly 100,000 times a minute.

The turbo is also benefited by the work of the MGU-H and MGU-K.


The MGU-K - Motor Generator Unit, Kinetic - is one of the most complex pieces of the F1 Power Unit, performing several roles.

Formula 1 braking generates massive amounts of heat - so intense that brake pads glow red with all the energy they are forced to absorb. Operating at around 1000 degrees Fahrenheit, the MGU-K can take that energy and regenerate it into electricity that can be fed into the ES (Energy Store).

The MGU-K is not just a generator, however - it also deploys energy from the ES to the drivetrain, giving the car up to 160bhp of additional power when required. This energy can also be deployed to the MGU-H to support the turbo.


The MGU-H - Motor Generator Unit, Heat - uses heat from the car’s waste exhaust gases to drive a generator - the same way the MGU-K uses energy. This converted energy can be sent directly to the ES or the MGU-K.

The MGU-H has the ability to work in both ways. It can suck energy out, or, put energy back in. Primarily it works to support the turbo, helping the compressor get back up to speed when you re-apply your foot to the accelerator – minimising Turbo lag, and maximising performance.


The Energy Store is a specialist battery specific to each Formula 1 Power Unit that stores electricity harvested from the MGU-K and MGU-H.

Since electrical energy is generated both by the extreme forces developed from braking and the heat emitted from the exhausts, it is an essential power source. Storing the recovered energy within the car is a must so that it can be utilised when needed. Over a single lap the maximum amount of energy that can be deployed from the ES to the rear wheels is 4MJ. That provides roughly an extra 30 seconds of power per lap.

Without the ES, we wouldn’t have the hybrid cars that we run today.


The Power Units Electronic Control Unit (ECU) checks and controls electrical elements of the PU, millions of times every second. It is crucial in ensuring that the driver has the right amount of power at the right time throughout a race. Controlling the Input, output and generation of energy, the ECU enables the whole Unit to create its power.