HRC LPL Tetsushi Kakuda Discusses Key Points of the New Power Unit Regulations and the Development Focus of Honda’s PU｜Features｜F1

From the perspective of a development engineer, what do you see as the main challenges and key points of the power units from 2026 onward?: “In terms of difficulty—honestly, everything. Other than the basic architecture of a V6 turbo internal combustion engine (ICE), everything is new, so it was essentially a complete reset. The basic structure, such as engine mounting distances and positions, does change, but overall it’s not dramatically different from before. However, the internals are completely different: the combustion system and the fuel have changed, so the requirements are entirely new. In that sense, it really is a new engine.; “With the elimination of the MGU-H, we have to rethink how we use the turbocharger. The compression ratio is more restricted, variable intake systems are no longer allowed, and deciding what kind of engine to build has become a completely new challenge.; “On the electrical side, output increases significantly, and the amount of energy flowing in and out of the battery and the control electronics (CE) becomes enormous to match the motor. That means we have to develop an optimal battery and CE capable of controlling it optimally. In short, this is a power unit that requires entirely new development across the board.”

It’s often said that removing the MGU-H simplifies the structure. What is your view on that?: “In terms of mechanical complexity, having an MGU-H does make the PU more complex. However, under the new rules the amount of electrical energy is much larger, so even small differences can translate into clear performance gaps. That’s what is different from before. So even if the system is simpler in structure, the level of difficulty remains very high.; “Energy management will also be a differentiating factor, particularly in deciding where to use the limited amount of energy. In principle, it’s best to use as much as possible on the straights, but depending on the car’s characteristics, you might choose to use it between short corners. That would then reduce the energy available on the straight, for example.; “There are also cases where electrical energy is used to shape torque characteristics or achieve peak power, depending on how the turbo and engine are designed. With the MGU-H gone, turbo lag becomes a major issue, and using electrical energy to compensate for that is certainly an option. However, electrical energy is limited—you can’t use it anytime, anywhere—so how you use it becomes extremely important.”

Is it fair to say that electrical energy is always in short supply? If so, doesn’t that makes both generation and usage extremely challenging?: “Exactly. The key point is how efficiently you generate the limited electrical energy and how you use it. It’s not just about power assist—this will vary depending on ICE characteristics, the circuit, race conditions, and even the driver’s style. That requires extremely fine control, which makes it a very challenging area.”

How about durability and reliability? Under the previous regulations, there were many issues early on, especially with the MGU-H.: “With reliability, we certainly experienced firsthand how difficult the MGU-H was. This time, we don’t have those unknown rotational speeds or extremely complex mechanisms, so I don’t expect failures on the same scale. That said, there are still definite challenges.; “For example, with the increase in electric output, the effects of high torque on the MGU drivetrain become a difficult area. Thermal management and temperature control of the battery and motor are also areas where each PU manufacturer may take a different approach, and that will inevitably affect reliability.”

Does the use of sustainable fuels also have a major impact?: “It does. The regulations themselves, including fuel composition, have changed completely. While we do have some knowledge, we need to start fresh in terms of how to match the fuel with new hardware and understand what effects are produced by different components. That’s why we really feel the difficulty of this as completely new development.; “With the strict constraints on producing and using fuel sustainably, fuel development becomes a battle of ideas and speed.”

Will batteries also become an area where performance differences emerge under the new regulations?: “The total capacity doesn’t change, but the amount of energy flowing in and out increases, so differences will appear in terms of energy loss and deployment duration. Performance degradation due to aging will also become a factor affecting overall performance.”

Specific details of development of Honda’s PU are undoubtedly confidential, so what is your perspective and thinking? What has been the focus in Honda’s PU development?: “There are many new elements, all of them important, so there’s nothing we can afford to neglect. That said, I believe the ICE is where differences are most likely to emerge. How much output you can extract from the ICE, and how you achieve high performance together with the new fuel, is extremely important.; “From our perspective, the high-speed combustion approach that delivered results with the previous PU is now largely unusable due to compression ratio limits and changes in fuel flow. That means we have to find new ideas to improve performance. Other manufacturers are in the same situation, so it really becomes a competition of ideas.”

When it comes to the battery, is it fair to think that the performance advantage from the previous PU can be carried over?: “That’s what we believe—and what we hope. Even after the decision to end our activities, battery development continued, not limited to F1 alone. Because of that, it has evolved further, and it’s an area we’re confident in.”

Regarding energy management, Honda has continued racing through its technical partnership with Red Bull Powertrains. Would you say you have ample experience and data in this area?: “Yes, in that sense we do want to compete by making full use of battery performance and energy management. However, the situation for energy management is completely different from before.; “Until last year, roughly half the energy was generated by the MGU-H and half by the MGU-K, so the proportion of how the MGU-K was used wasn’t overwhelmingly large.”; “In particular, energy could be transferred directly from the MGU-H to the MGU-K, so how well the MGU-H performed made a big difference. The MGU-K harvested energy under braking, but because it was relatively small, differences were limited. Now, everything relies on the MGU-K, so our entire approach to energy management has been reset.; “Having experience and data is certainly better than not, and I believe it will be useful to some extent. But in reality, there are still many things we won’t know until we actually try.”

With winter testing and the season opener approaching, what is the current situation?: “The specifications for the 2026 season are essentially fixed, and our current focus is on improving reliability ahead of homologation. However, there are many things you can only learn by installing the PU in a car and actually running it. That’s why winter testing—mounting it in a real car or one that’s very close to race conditions and confirming that everything operates properly—is an extremely important task, and that’s the stage we’re at now.”