This case study covers how ToffeeX, UniBo Motorsport, and BI‑REX designed an integrated electric motorsport cooling system for their award-winning MotoStudent electric racing motorcycle, combining physics‑driven generative design with additive manufacturing.
Summary
UniBo Motorsport partnered with ToffeeX and BI-REX to create an innovative integrated cooling system for electric motorsports for their MotoStudent electric racing motorcycle that would fit tight packaging constraints while handling the extreme thermal loads of racing.
Using ToffeeX’s physics-driven generative design and BI-REX’s additive manufacturing capabilities, the team produced a topology-optimized integrated tank/cooler that simultaneously cools both the motor control inverter and the liquid cooling circuit, using dry ice sublimation as the primary cooling medium.
Experimental testing confirmed that the exchanger dissipates nearly 900 W of thermal power and achieves its best performance between 7.65 and 10 L/min of coolant flow, where the internal flow is strongly turbulent and the global conductance UA reaches a plateau.
In this regime, the thermal bottleneck shifts from the exchanger geometry to the cryogenic cold side, demonstrating that the design pushes the system close to the physical limit of the boundary conditions rather than the hardware itself.
From initial requirements to a race-ready component took approximately two months, validating the speed and effectiveness of this integrated design-to-manufacturing workflow.
Project Context: designing an integrated cooling system for electric motorsports
Electric motorsport teams are pushing battery and inverter power levels higher every season, but the cooling hardware has struggled to keep up. Traditional radiators and air‑cooled systems are bulky, drag‑heavy, and inefficient in short, high‑intensity stints on track.
The primary thermal challenges in electric racing arise from three sources:
- Power electronics — inverters and motor controllers that switch large currents at high frequencies, generating significant heat at the semiconductor junctions
- Traction motor — generating substantial waste heat in windings and rotor under race loads
- Battery pack — requiring tight temperature control to maintain performance and avoid degradation
Each source has different temperature sensitivities and cooling requirements, which traditionally means separate circuits, separate components, and a heavy, complex system.
UniBo Motorsport’s MotoStudent motorcycle faced a particularly acute version of this problem. The compact design envelope of a racing motorcycle leaves almost no room for cooling infrastructure and every component must earn its weight and volume.
The team needed to cool the inverter and motor simultaneously while minimizing system weight and volume: a set of objectives that pull directly against each other.
Rather than adapting conventional cooling architectures to electric racing constraints, the team asked a fundamental question:
What does an optimal thermal management system look like when you remove conventional manufacturing limitations?
This is where physics-driven generative design and advanced additive manufacturing converged.
The Application: Electric Motorcycle Thermal Management
Modern electric racing motorcycles generate substantial thermal loads despite their inherent efficiency advantages over combustion engines. The power electronics alone, specifically the inverter converting battery DC power to three-phase AC power for the motor, can dissipate tens of kilowatts during a race. This heat must be managed to maintain inverter junction temperatures within safe operating windows (typically below 80-100°C depending on semiconductor technology).
Simultaneously, the liquid cooling circuit that manages motor winding temperatures must remain within operational limits to sustain continuous power output. In racing conditions lasting 15-45 minutes, depending on track and event format, any thermal throttling or component de-rating directly reduces available power and ultimately race performance.
UniBo Motorsport’s approach was to integrate both cooling functions into a single system: a compact tank that serves simultaneously as an inverter cold plate and a motor coolant tank. The innovation came through the internal geometry. Rather than using traditional fin structures or simple rectangular passages, ToffeeX generated a topology-optimized cooling structure tailored specifically to each function.
Crucially, the system was designed to operate with dry ice sublimation as the primary cooling medium. For a race weekend, the team pre-cools the tank with dry ice before each session, allowing CO₂ sublimation to provide continuous, passive cooling throughout the run.
Design Process: Physics-Driven Topology Optimization
ToffeeX’s role in this project centered on solving a complex multi-objective optimization problem: optimizing heat transfer and pressure losses for the inverter and the ice tank, combining them into a single, manufacturable component.
Problem Definition
The design process involved two separate optimizations: one for the cold plate, using algorithms suited for forced convection, and another for the ice tank, employing optimization methods for natural convection and conduction with the dry ice pellet.
We identified two main design domains:
- Cold Plate Design Domain: This area, in direct contact with the inverter, was optimized to maximize heat transfer from the electronics to the cooling fluid, leveraging forced convection principles.
- Dry Tank Design Domain: Here, the objective was to maximize the internal surface area available for contact with the dry ice pellet, while minimizing weight in accordance with predefined limits, accounting for heat transfer via natural convection and conduction.
Optimization Approach
Although the optimization workflows for the cold plate and ice tank were decoupled, we carefully set boundary conditions in each case to account for the presence and thermal influence of the other component.
For instance, when optimizing the cold plate, a heat transfer coefficient was specified at the tank boundary to simulate the actual interface with the dry ice chamber.
This approach ensured that, while each subdomain was optimized independently, the thermal interactions were adequately reflected through realistic, physically meaningful constraints and parameters.
Using ToffeeX’s physics-driven generative design platform, we manage to:
- Maximize thermal energy transfer from the inverter heat source to the cooling system, accounting for phase-change behavior as dry ice sublimes
- Optimize motor coolant flow distribution to ensure uniform cooling across the entire motor cooling jacket circuit
- Minimize pressure losses in both circuits to reduce parasitic power requirements
- Respect manufacturing constraints inherent to SLM technology, including minimum wall thickness (typically 1-1.5 mm) and overhang angle limitations
The team explored multiple variants by adjusting the relative weighting between heat transfer maximization and pressure loss minimization, enabling them to understand the full design landscape.
This iterative approach took weeks rather than months compared to traditional CFD-driven manual design refinement, dramatically accelerating the development cycle while ensuring the selected design represented an informed choice rather than an intuitive guess.
Design Selection
From the multiple optimized designs generated, the team selected a final geometry balancing three critical factors for motorsports applications:
- Thermal performance sufficient to maintain inverter and motor temperatures within safe operating windows throughout a race
- Pressure losses within the motorcycle’s thermal management power budget
- Manufacturability via SLM, including structural integrity and the ability to withstand race-day conditions
The Manufacturing Process: Selective Laser Melting
BI-REX Competence Center employed selective laser melting (SLM) to manufacture the optimized cooling component. SLM is a powder-bed fusion additive manufacturing process uniquely suited for this application.
The process enables geometric complexity impossible with conventional manufacturing: complex internal channels, optimized surface features, and integrated structures that would require expensive multi-step assemblies if manufactured conventionally.
SLM enables three things that were critical here:
- Geometric Freedom: topology-optimized cooling channel geometries that would be impossible to machine, cast, or stamp. Internal channels can follow the physics-optimal flow paths rather than simple rectangular designs.
- Integrated Design: multiple components are fabricated as a single integrated part, eliminating assembly operations and potential leak points.
- Reduced Weight: the optimized internal geometry and lack of unnecessary material mean the final component weighs substantially less than conventional designs. A critical advantage in racing, where every gram affects performance.
Experimental Testing & Performance Highlights
To validate the design under realistic conditions, UniBoMotorsport ran a dedicated test campaign using dry ice as the cooling source. The objective was to quantify the exchanger’s maximum heat dissipation and global thermal conductance (UA) as a function of coolant flow rate through the system.
Pump speed was varied to sweep a range of water flow rates, from low flow representative of off-load conditions, to high flow representative of full-push on-track scenarios.
The results confirm that the ToffeeX-designed exchanger dissipates up to approximately 895 W of thermal power with dry ice as the cold sink in a component compact enough to install in a racing motorcycle.
As flow rate increases, UA rises steeply up to about 7.65 L/min, marking the transition into a strongly turbulent regime inside the exchanger. In this regime, the coolant-side heat transfer becomes highly efficient.
Optimal operating window
The sweet spot is between 7.65 and 10 L/min (approximately 900–1200 pump rpm), where the system delivers the best trade-off between:
- Heat dissipation
- Temperature control and stability
- Pressure drop and pump effort
Within this window, the UA curve begins to plateau: pushing more flow no longer produces proportional heat transfer gains. This is not a design limitation: it is the signature of a design that has done its job. The thermal bottleneck has shifted from the exchanger geometry to the dry ice cold side, meaning the component is operating at the physical limit of the cryogenic boundary condition, not the design envelope itself.
Operational boundaries
At flow rates below roughly 3 L/min in cryogenic conditions, the tests revealed:
- Increased tendency for internal ice formation in the coolant passages
- Transient temperature spikes at the outlet
- Fluctuations in measured thermal power and conductance
These low-flow operating points are not recommended for cryogenic use. Keeping the system within the tested optimal window ensures stable, repeatable cooling performance across a full race weekend.
When operated correctly, the exchanger consistently delivers a power density that is very difficult to match with conventional convection-based cooling hardware — validating ToffeeX’s physics-driven generative design approach for high-demand electric motorsport applications.
Conclusion
The collaboration between UniBo Motorsport, ToffeeX, and BI-REX demonstrates what becomes possible when you stop designing around manufacturing limits and start from the physics.
The integrated inverter/water cooling component represents more than an incremental improvement over traditional designs: it is a different category of solution. A single topology-optimized part replaces what would traditionally be multiple components, fabricated and assembled separately, each with its own compromises.
For UniBo Motorsport, this innovation provides a critical competitive advantage in MotoStudent racing. For the broader engineering community, the project illustrates a clear path forward: advanced thermal challenges aren’t solved by incrementally optimizing existing designs, but by removing manufacturing constraints that force compromise in the first place.
About UniBo Motorsport
UniBo Motorsport is the official motorsports team of the University of Bologna, Italy. Competing in the prestigious MotoStudent international championship, the team designs, builds, and races lightweight electric motorcycles. The competition emphasizes integrated systems design, where aerodynamics, thermal management, battery optimization, and control systems must work in concert to achieve competitive performance.
About BI-REX Competence Center
BI-REX is a specialized competence center focused on advanced manufacturing, design optimization, and materials engineering. The center provides expertise in selective laser melting, design for additive manufacturing, and process optimization, translating computational designs into manufacturable, high-performance components.