Creating a Custom CPU Water Block for an Autonomous Racecar

Revolve NTNU needed a custom water block capable of maintaining optimal operating temperatures of their Autonomous Racecar’s Processing Unit. We created a lightweight (253 grams/0.55 Pounds including water and mountings) liquid-cooling solution that complemented the existing design and kept operational temperatures of the Processing Unit under 65°C (140°F) , never reaching thermal throttling.

Background

The future of motorsports is definitely electric and autonomous. While commercial autonomous vehicles are yet to become available on the market, autonomous racecars are already gaining much traction and are changing the motorsport industry landscape as we speak.   

For these vehicles to reach optimal levels of functionality, their systems must deploy a holistic software structure containing multiple individual driving functions. To achieve this and mitigate system failures that may lead to losing an entire competition, these systems require a stable, high-performing Processing Unit operating at optimal temperatures and never reaching thermal throttling.

Revolve NTNU

is the Norwegian University of Science and Technology's team for Europe's Formula Student motorsport competition. Their 2022 car, Aurora, was the first vehicle to compete in both electrical and autonomous competitions, which is when they faced increased complexities in designing the mechanical, electrical, and software systems this racecar required.

The Challenge

Revolve NTNU’s racecar already features a water-cooling loop that cools the motors and inverters. This time their team needed a water-cooling solution for the vehicle’s Processing Unit . Since they already had a loop in place, we had to design a water block that would connect to the existing loop without negatively affecting the airflow.

Results: PU Operating Temperatures Reliably Kept Under 65°C

During all the intense testing periods and all competitions, the water block kept the Processing Unit’s operating temperatures under 65°C(140°F) , never reaching 70°C which is where thermal throttling occurs and can lead to system failure. The design was highly lightweight, weighing only 253 grams (0.55 Pounds) including water and mountings.

"For Revolve, reliability is key," says Joakim Saugen, Revolve NTNU’s Cooling System Engineer. "If the PU throttles, it might cause our autonomous systems to fail, causing us to lose the entire competition. It is therefore important to have a reliable solution. We did not experience thermal throttle with the EK cooling block at any stage during the testing and completion period."

Performance, Reliability, Longevity, Ease-Of-Use, High Build Quality – ALL in Focus

The water block is being used in a harsh operating environment - the sidepod of a racecar. Heavy vibrations and high G forces can easily cause leakages unless the water block and its connections are not properly designed and constructed.  

"We did not experience any leakage during the testing and competitions period,” Joakim adds. “In addition, all the bolts and holes for the bolts are in a high-quality shape. The material did not seem to show any high marks of strong usage."

The technologies and materials used include precisely machined aluminum coldplate and POM top cover, with everything sealed using EPDM rubber gaskets and screws to join the two parts. The standard G1/4 BSPP inlet and outlet ports enable reliable connection to the peripherals in the cooling loop. The use of high-quality materials led to no signs of wear and tear after an entire racing season. "We can use it for another season," Joakim adds.