How could Honda have gained 223bhp?

According to Spanish publication AS, the Japanese manufacturer would have achieved a major breakthrough in unlocking 223bhp on its power unit divided up as follows: 60bhp from the internal combustion engine (ICE) and 163 from the energy recovery systems (ERS).

For starters, the ERS comprise four elements: the MGU-H, the MGU-K, the battery, and a pair of control boxes. MGU stands for motor-generator unit. When acting as a generator, the device converts the mechanical and heat energy that it receives into electrical energy. When operating as a motor, it is the opposite.

The current 1.6-litre V6 turbocharged power units feature two MGUs: the MGU-H (for heat) absorbs power from the turbine shaft to convert heat energy from the exhaust gases, while the MGU-K (for kinetic) recovers some of the kinetic energy dissipated under braking.


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RESTRICTIONS ON THE MGU-K

Looking at the diagram available in Appendix 3 of the technical regulations, the battery, also known as energy store (ES), can feed up to 4MJ/lap to the MGU-K, which then transfers a maximum power of 120kW (or 163bhp) to the engine (actually the drivetrain). If the settings have been adjusted to deliver the full 120kW, then the 4MJ are used up in 33.33 seconds.

It is worth recalling that these 4MJ could be deployed over a longer period of time, provided that the 120kW power be graduated, depending on how much pressure the driver applies on the throttle. It is actually impossible to know exactly for how long the energy can be dispensed, and F1 technical expert Matthew Somerfield has brilliantly explained why the 33.33s are a misnomer.

If you surmise that the battery of the all-conquering Mercedes power unit does send 4MJ to the MGU-K, the engine can then deliver an extra 163bhp horsepower for 33.33s on each lap. Now, if Honda’s energy store could, for one reason or another, only supply half of the maximum 4MJ last year, this means the Japanese power unit could only use the 163bhp for 16.66s (or 81.5bhp for 33.33s). Fernando and Jenson Button’s straight-line speed deficit was painfully obvious at power tracks like Spa-Francorchamps and Monza.


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MGU-H – A DUAL-FUNCTION COMPONENT

One should remember that the MGU-K can receive energy directly from the MGU-H, and this without any restriction. What’s more, the MGU-H can also feed as much energy as it can to the battery. In other words, it has a dual function: charging the battery and supplementing the MGU-K.

The regulations state that the battery can only receive 2MJ from the MGU-K when the latter acts as a generator. In order to deliver the maximum 4MJ, the energy store benefits from the contribution of the MGU-H, from which it can transfer up to 2MJ to the MGU-K.

As a result, the overall power that the MGU-K can return to the drivetrain amounts to: 4MJ (from the battery) + xJ (which comes straight from the MGU-H). If we surmise that Mercedes’ MGU-H is potent enough to supplement the MGU-K, then the Silver Arrow can use the 120kW mentioned earlier for a longer period of time than 33.33s.

All in all, reporting a 163bhp horsepower gain for Honda does not make much sense. First, it implies that last year’s RA615H did not recover any energy (not even under braking). Then, it would be more accurate to talk about energy recovery and deployment and how much longer the extra power can be used. But obviously that would make for a less catchy headline… F1i.com