Sergio Perez, Red Bull, Autodromo Hermanos Rodriguez, 2021

How F1 can push “the world’s most efficient engine” even further

2021 F1 season

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Formula 1 is finally trumpeting the incredible efficiency of its V6 hybrid power units. But with new power unit regulations for 2026 on the table, can it extract even more performance per drop of petrol?

F1 first introduced mild hybridisation with the Kinetic Energy Recovery System, KERS, in 2009. This was an optional add-on to the V8 engines used at the time.

Given the much lower minimum weight of an F1 car in 2009 – 640 kilograms compared to 752kg today and 792kg next year – teams were divided on whether to add KERS to their cars. Among those who didn’t were eventual champions Brawn and closest rivals Red Bull even though their engine suppliers – Mercedes and Renault respectively – produced the hardware for other teams.

Back then, the electric motor was restricted to delivering a maximum of 60kW (80.4 horsepower) at any one time and just 400kJ per lap – a tenth of a kilowatt hour. The 2009 sporting regulations list any energy “which may be recovered at a rate greater than 2kW must not exceed 20kJ,” a truly tiny amount for an F1 braking event.

The numbers were so low that it made the additional weight of the hybrid xsystems unattractive. Some even suggested this was deliberate, a product of F1’s image of itself more linked to raw engine power and rejecting greener ideas, at the time.

Just over than a decade later every car maker is scrambling to electrify their ranges. Pure combustion-powered cars not just going into a decline of development but an increasing number of countries have ruled out from sales of such cars from the 2030s.

Lewis Hamilton, McLaren, Hungaroring, 2009
Hamilton gave hybrid power its first F1 victory in 2009
F1’s current hybrid system has been the subject of a lot of handwringing since it was introduced in 2014, with concerns ranging from the aesthetic – inevitably, hybrid systems sound different to combustion power alone – to concerns about cost and complexity. The sport’s animosity towards the systems, even as they were introduced, came right from the top: CEO Bernie Ecclestone said he hated the hybrids and wouldn’t have introduced them if there’d been another palatable solution.

For a long time hybrids were treated as something forced onto F1. This was surprising for something that manufacturers were spending so much money on developing and which teams had to dedicate so much resource to understanding and managing.

This has changed since Liberty Media took over F1 four years ago. Now, as the series attempts to agree new power unit regulations for 2026 and by doing so courts a potential new supplier in the shape of the Volkswagen Group, it’s finally taken a turn to celebrate the systems that power the current cars. One can’t help but wonder whether Honda would have been more open to staying in the sport if F1’s own marketing had supported the green technology message it had to take to the board to justify funding its programme.

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The choice of wording – “the world’s most efficient engine” – will provoke debate. No engine designed for being flung around a track at 300kph in a chassis will actually be the most efficient compared to, for example, static generators.

The V6 hybrid turbo era began in 2014
But in corporate terms F1’s move to start describing and promoting the power units rather than treating them as a dirty secret, is a pretty big one. After all, they’re actually quite clean.

The figure that F1 has issued for the current power units’ overall efficiency is 52%, which is a staggering amount compared to average petrol engines making about 20% thermal efficiency. That’ includes the hybrid recovery system and is a huge increase, compared to 29% at the end of the V8 era. For comparison, the Toyota Prius road-going hybrid has 40% efficiency, itself a huge number for a production car but significantly short of crossing the halfway point of what energy is in the fuel burned and what energy is output by the engine.

The 50% mark was the white whale of combustion efficiency for a long time and F1 is right to be proud that its technology exceed that. However, regulations also restrict recovery and effectively kneecap the MGU-K, meaning there are still big advances to be made, which could be particularly tested in high-performance conditions on a race track in ways it’s hard to simulate elsewhere.

Right now, the MGU-K is restricted to recovering just two megajoules of energy per lap, a little over half a kilowatt hour. Overall, with MGU-H’s recovered energy, drivers can use 4MJ of energy from the battery, over a single lap, which amounts to 1.1kWh.

The system is further restricted by only being able to recover or deliver 120kW at a time. This is significantly lower than higher-end battery-electric road cars now. The Mercedes EQS recovers at up to 295kW under braking, which it could be assumed to do considerably less often and less hard than an F1 car.

F1 hybrid logo
New graphics will promote F1’s hybrid power units this weekend
Electric motors have much greater efficiency. Formula E powertrains operate so close to 100% efficiency that gains are verging on the physically impossible. With higher limits on regeneration (at up to 250kW and with unlimited energy recovery) FE regenerates more under braking than F1 over the course of a much shorter lap, which is something neither series seems keen to mention, possibly out of politeness to F1’s regulation-capped systems.

Almost all senior motorsport categories are introducing hybrid elements. But with the World Endurance Championship’s Hypercar category (which replaced the pioneering hybrid LMP1 class) horsepower-restricted, and LMDh using spec hybrid elements, F1 is the only series that allows full hybrid development, next year’s freeze notwithstanding.

The opportunity to push hybrid systems to genuinely extraordinary levels of efficiency is definitely there for the taking in the 2026 regulations. The MGU-H is expected to fall by the wayside, but taking the training reins off MGU-K presents a colossal chance to push every element of the recovery system, from battery management and material improvement to pushing the upper limits of what can be done with regenerative braking, something the automotive sector is still tip-toeing its way into exploring.

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Author information

Hazel Southwell
Hazel is a motorsport and automotive journalist with a particular interest in hybrid systems, electrification, batteries and new fuel technologies....

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20 comments on “How F1 can push “the world’s most efficient engine” even further”

  1. This future sounds very boring (figuratively and literally).
    I have little doubt that it’s setting tech nerds, engineers and greenies’ loins on fire – but for car and motorsport lovers it’s about the least interesting thing associated with modern F1.

    Green up the fuel and let them burn it with a proper engine that people actually want to learn about and enjoy. Something we can relate to. Entertaining and exciting on many levels.
    Nobody dislikes F1’s engines from the 90’s – which had a healthy (and now unimaginable) 8 manufacturers participating in 1990 alone, let’s not forget.
    How many manufacturers want to play F1 now? Just 3. Are we really sure these are the right engines?

    1. Let them run a v10 from the 90s on the current fuel limit. You all see how fun that is.

      1. The current fuel limit is garbage, as is having to carry it all from the start of the race.
        Anyway – the greener that fuel is, the less it matters how much of it is used.

        And yes – let them. The rules are far too restrictive now.

    2. Can wholeheartedly say that a lot of new fans – and F1 needs new fans – are extremely interested in the hybrid systems.

      V12s are for classic car shows, now.

      1. Very few are interested in hybrids.
        Most new fans are interested more generally in racing. Given that this is a racing series…
        A large percentage of them seem to follow drivers much more than cars or anything technically related. Whatever is shoved in their faces on social media.

        Doesn’t have to be V12’s, either. 1990 (as the going example) had V8’s and V10’s as well as a Flat-12 and a W-12.
        Only two years earlier F1 was running 4 and 6 cylinder engines as well.
        Yay for diversity.
        Isn’t Lamborghini producing a V12 hybrid? Surely that’s a bit more relevant to F1 than what Grandma drives to the shops on Sundays.

        1. 62.6% of respondents to the 2021 F1 fan survey said that F1 has exciting technology, over 60% said that a key feature of F1 was that it had to have pioneering tech, above any other key feature. 67% of respondents are aware of an support F1’s sustainability, 66% of respondents also backed F1 looking into sustainable fuels but that’s to be viewed in combination with the other responses. Although the survey was far from methodologically perfect, people are interested in this.

          People ask me about it loads, especially when they’re just getting into the sport. It’s a fascinating bit of technology.

          1. I think the majority of those people would still say F1 was great and the technology was interesting regardless of whether hybrid systems were used or not.
            As you mention @hazelsouthwell, the tech in F1 is, or can be, interesting (if not actually relevant to the wider motoring world) – but hybrid systems are not the only tech incorporated. Sustainability means much more than just the hybrid system, too.
            Sustainable fuels are important regardless of which engine they are running through.

    3. I am a long time motorsport fan, and I find the development of modern F1 engines to be a very interesting subject. I think that the future sounds more interesting than the past, and have no doubt that there will be many surprising developments to come in the next few decades. There are plenty of racing series to watch if you want a nostalgia fix.

  2. Martin Elliott
    11th November 2021, 13:26

    So the K-MGU is more efficient than an ICE, but is limited by the FIA energy & power regulations.

    But compared to the ICE, what is that efficiency, including the ES storing and supplying that energy. Judging by the radiator pack to cool the ES, a fair bit in both directions. In fact, as the ES charge can only be implied, FIA regulations state it assumes 0.75 efficiency when charging!! Nobody ever mentions that in these articles.

    1. As long as there’s a hard limit on the amount that the MGU-K can recover per lap (the potential for which massively exceeds 2MJ) there will be huge amounts of energy lost from it in heat because that’s the only place it can go, after being recovered from a braking event. Energy recovered from the brakes doesn’t have to go back into the battery but does have to go somewhere, so it mostly gets vented out. More recovery = less need to bleed off heat, so greater efficiency.

      But in any case that bit doesn’t really get measured, per se, when looking at thermal efficiency that starts with a combustion fuel; the % is of the KJ of energy in the starting fuel that then translates to KJ of energy that are ‘usefully’ run, ie: to create drive. What’s recovered from the hybrid system is counted against the starting energy figure but not eg: relative to what is lost through the MGU-K efficiency. (whether that should be the case or not, I think is an interesting question but that is how it’s done)

      F1’s energy stores are direct-liquid-cooled (battery cells sit surrounded by liquid, that’s circulated within the battery construction) so have relatively minimal airflow requirements compared to the MGU-K itself needing to cool down from braking.

  3. I’m curious to know how efficient the ICE is by itself, without the recovery systems.

    1. In a 1:1 comparison? It would be terrible.
      It’s designed to work within a certain environment – as in, with all that stuff attached. Remove one part, and the whole system collapses.

  4. Without the MGUH much of the 52% efficiency figure will fall as exhaust gasses will just blow right out the bum wihout any electrical contribution.

    I think this is a bad move because some street cars are coming out with electrified turbochargers. What FIA should have done is allow existing PU manufacturers to license VW/Audi/Porscbe their MGUH technology or even just sell them the parts.

    1. Although I think getting rid of MGU-H at this stage is borderline redundant (it should be something teams can choose or not choose to do, IMO, with an overall upper limit to recovery per lap) it does simplify the system management for the power unit. And given the huge amount left on the table that could be being recovered through MGU-K, if it wasn’t effectively kneecapped by the regulations, MGU-H feels frivolous by comparison.

      MGU-K has the benefit of improving braking performance so has an actual sporting effect – 80%+ of high speed braking is regenerative and then a lot of that energy is just lost as heat, currently.

  5. Glad to see they are doing this, finally.

  6. They should switch to manual deployment, where it should be very noticeable for the viewer, if the driver uses the hybrid system. For example Hamilton pulls his boost paddle to deploy the hybrid energy, than the viewer will see a blinking Merc EQ-Power logo on screen. The same for Honda, Renault, Ferrari ofcourse.

  7. F1 needs to have more electrification in their cars. Eventually F1 cars will be 100% electric, the only thing stopping it from happening now is the battery technology isn’t good enough. Petrol has an energy density in the region of 44.4 Megajoules per kg, while lithium ion batteries have an energy density of slightly less than 1 MJ/kg. So it will be hard for battery technology to beat petrol.
    If you consider an average race might entail something like 70 laps, and that a car might carry 105 kg of fuel, then a 100 kg battery might hold enough energy for an F1 car to do several laps of a race track. Maybe some sort of rapid charging system would work, where the battery is recharged while the car is being driven along part of the race track at 350 km/h or whatever. Then the battery would supply the electricity for the rest of the lap.
    F1 does need to design their rules to encourage teams to use more electricity. It is like F1 has this fixation with a 1.6 litre V6 engine. A manufacturer might have a 4 cylinder or 8 cylinder engine or a 2 litre engine they want to supply to an F1 team, but F1 won’t allow it. F1 has fuel flow restrictions, which should provide some equality between engines of different sizes.

  8. I find it quite amazing that the current thinking for cars is that they will go over to being solely EV by the end of the decade if not sooner.

    At no point has anyone really considered marrying up super efficient and very small capacity ICE’s to hybrid technology as the way forward yet it seems that there still exists massive potential for that. It would be far easier in countries like Australia, Canada etc where there are huge distances and not a large infrastructure for EV to introduce hybrid technologies for cars, trucks, trains etc but seems to be no appetite at all for it.

    Given that this article suggests that the technology is being under utilised massively in F1, one has to ask the question why. Is it a case that the motor vehicle manufacturers see an opportunity for more profit from EV only rather than the “green” reasons they are all professing to be following?

  9. MGU-K was restricted to allow the MGU-H not to be. The MGU-H system is much more advanced; regenerative brakes are decades-old (found on electric trains and yes, Priuses) while recovering heat energy to electricity, and driving the turbo with a motor to eliminate turbo lag, are novel technologies.

    You should ask, Hazel, but aiui you can’t break 50% efficiency with even unrestricted regenerative braking; exhaust heat recovery is needed.

    Tesla and Nissan drove (pardon the pun) BEVs into the mainstream faster than the rest of the car industry expected and MGU-H units are extremely expensive, so the tech never found a place on the road.

    It would be a shame to lose them, but as Honda demonstrated, they’re extremely hard to develop. VAG doesn’t have the money or the ability to do it, so they can’t build a F1 PU which requires one.

  10. If Europe and UK are going to totally ban ICE by 2035, F1 should be strategizing to transition away from it now.

    Does anyone know if ICE running on Synthetic fuels will be allowed? Has the law thought that far ahead? I would think VW’s interest shows that perhaps synthetic fuel burning ICE will be legal.

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