2026 F1 Cooling: Why Bigger Radiators Are Needed

Keeping a Formula 1 power unit within its operating temperature range is one of the most demanding thermal engineering challenges in racing. Every component that converts energy from one form to another generates heat as a byproduct, and the 2026 power unit generates significantly more heat from its electrical system than the previous generation did. The MGU-K’s tripled power output from 120kW to 350kW means the electrical system produces nearly three times as much waste heat per unit of time, and this additional thermal load must be managed through cooling systems capable of extracting and rejecting it without adding excessive mass or aerodynamic drag to the car. The result is a cooling architecture that is larger, more complex, and in some respects more technically innovative than any previous Formula 1 generation has required. For context on the full power unit changes driving this thermal challenge, see our guide to the 50/50 power split in 2026 F1.

Why the 2026 Cooling Demand Is Higher

The total heat that a Formula 1 power unit must reject through its cooling systems comes from every component where energy conversion efficiency is less than 100 percent. The combustion engine rejects heat through the cooling water circuit, which passes through the radiators in the sidepods, and through the exhaust gases that exit the system carrying thermal energy. The MGU-K generates heat in its windings and rotor through electrical resistance losses during both driving and harvesting operations. The Energy Store generates heat during charging and discharging through the internal resistance of its cells. And the power electronics, inverters, and control systems that manage all the electrical flows generate their own heat as a byproduct of processing high power levels.

The MGU-K’s Thermal Contribution

A 350kW MGU-K operating at typical efficiencies for high-performance electrical machines generates heat at rates that are substantially higher than the 120kW unit it replaced. Even at 95 percent electrical efficiency, which is near the top of what is achievable for a racing motor generator unit, a 350kW machine generates approximately 17kW of waste heat from the motor itself. At the higher power densities where the 2026 MGU-K operates during peak demand phases, the instantaneous heat generation is higher still, and this heat must be extracted from the rotor and stator windings quickly to prevent the winding temperatures from exceeding the thermal limits of the insulation materials. An MGU-K that overheats reduces its efficiency, which generates more heat, creating a thermal runaway risk that the cooling system must prevent through adequate heat extraction capacity.

The inverter electronics that control the MGU-K’s power flow process the full 350kW at very high switching frequencies. These electronics generate heat proportional to their own inefficiencies, and at 350kW the heat generated even from small percentage losses is significant in absolute terms. The inverter’s thermal management is critical because semiconductor components in the inverter are highly sensitive to temperature: above their rated junction temperatures, the semiconductors degrade rapidly and can fail catastrophically. Teams invest heavily in the thermal management of their inverter packages, often locating them in positions within the car where cooling airflow is reliably available and where the thermal interface between the semiconductor package and the heat exchanger is as efficient as possible.

Energy Store Thermal Management

The Energy Store generates heat during both charging and discharging operations. The 4MJ delta SoC limit and the 9MJ per lap harvest limit ensure that the Energy Store is cycling through significant charge and discharge events on every lap, and the accumulated heat from these cycles must be managed across the full race distance. At the start of a race, the Energy Store is at ambient temperature and the thermal management system manages its temperature rise from that baseline. As the race progresses, the cumulative heat input from hundreds of charge and discharge cycles raises the cell temperatures within the Energy Store, and the cooling system must maintain those temperatures below the limits above which the cells’ performance and longevity begin to degrade.

The dielectric cooling systems that several manufacturers have developed for the 2026 Energy Store address this challenge more effectively than conventional cooling approaches. Conventional liquid cooling uses a coolant circuit that passes through channels in the battery pack structure, extracting heat through conduction from the cell surfaces. Dielectric cooling uses an electrically non-conductive fluid that can be circulated directly in contact with the cell surfaces or within the cell module structure itself, achieving better thermal contact and higher heat extraction rates per unit of packaging volume. The trade-off is that dielectric fluids must be managed carefully to prevent contamination that could change their electrical properties, and the circulation systems must be designed to prevent fluid contact with components that the fluid’s properties are not compatible with.

Radiator Sizing and Sidepod Implications

The radiators that reject the power unit’s waste heat to the ambient air are located in the sidepods on each side of the car. The sidepod inlet captures airflow from outside the car and directs it through the radiator cores, where heat transfers from the coolant circuits into the air. The heated air then exits through the sidepod outlet, which is typically at the rear and upper surfaces of the sidepod. The rate of heat transfer from the coolant to the air depends on the radiator’s core area, the coolant and airflow rates, and the temperature differential between the coolant and the incoming air. The bodywork rules that define how sidepods can be shaped are covered in our article on 2026 F1 bodywork rules.

Why Core Area Must Increase

A higher total heat rejection requirement with the same ambient air temperature and the same airflow rate requires a larger radiator core area to transfer the additional heat within the available temperature differentials. A car that needs to reject 20 percent more heat than its predecessor, due to the MGU-K’s expanded heat generation, requires either 20 percent more radiator core area, higher airflow rates through the same core, or coolant temperatures raised to increase the temperature differential driving the heat transfer. Each of these options has trade-offs: more core area means larger sidepods with more aerodynamic drag; higher airflow requires larger inlet openings that also affect aerodynamic performance; and higher coolant temperatures approach the thermal limits of the components being cooled.

Teams balance these trade-offs by optimizing the entire cooling system architecture rather than simply making the radiators larger. Advanced radiator core designs that achieve higher heat transfer coefficients per unit of core area, improved coolant flow distribution that eliminates hot spots where heat transfer degrades, and more effective inlet designs that maximize the airflow captured per unit of inlet opening area all contribute to meeting the higher cooling requirement with less total packaging volume than a simple scaling approach would require. The cooling system’s performance is one of the less visible but genuinely important competitive differentiators in 2026, since a car with a more effective cooling system can run tighter sidepods, which has a direct aerodynamic benefit, while still maintaining adequate thermal margins throughout a race.

Approximately 50 Degrees Celsius: The Dielectric Fluid Operating Point

Dielectric cooling systems for the Energy Store and power electronics typically operate with the dielectric fluid at temperatures in the range of approximately 50 degrees Celsius, which is lower than the temperatures at which conventional engine cooling water circuits operate. This lower operating temperature is necessary because the electrical components being cooled have stricter temperature sensitivity than the metal components cooled by the engine water circuit, and the dielectric fluid’s heat must ultimately be rejected to the ambient air through its own heat exchanger or through a shared circuit with another cooling loop. The approximately 50-degree operating temperature provides adequate heat transfer capacity from the electrical components while maintaining enough temperature differential above ambient air to drive effective heat rejection through the heat exchanger.

Managing a separate dielectric cooling circuit alongside the conventional engine water circuit and the intercooler circuit that cools the compressed intake air from the turbocharger adds complexity to the car’s fluid management systems. Leak paths between circuits with different fluid types can compromise both the electrical insulation properties of the dielectric fluid and the electrochemical stability of the water-glycol engine coolant. Teams develop their cooling system layouts to minimize the risk of cross-contamination while keeping the additional mass of the dielectric circuit’s pump, heat exchanger, and pipework within the weight budget available for cooling system components.

Cooling in Race Conditions

The cooling system’s performance must be adequate not just under the idealized conditions of steady-speed circuit running but across the full range of conditions encountered during a race weekend, including low-speed track conditions behind the Safety Car, high ambient temperatures at circuits like Singapore and Abu Dhabi, and the reduced airflow available when a car is following closely behind another car through multiple consecutive corners.

At Safety Car speeds, the reduced airflow through the radiator inlets dramatically reduces the cooling capacity of the sidepod radiators. Teams manage this risk through adjustable cooling flaps or louvre systems that can increase the pressure differential drawing air through the radiators at low speeds, and through temporary reductions in MGU-K deployment that reduce the electrical system’s heat generation rate during the Safety Car period. The balance between maintaining adequate cooling and maintaining competitive performance during a Safety Car restart is a real-time engineering challenge that teams prepare for with dedicated cooling strategies built into their race management procedures.