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Mercedes-Owned YASA Reveals a 737-HP Electric Motor That Weighs Just 29 Pounds

Last month, Mercedes-AMG touted the potential of YASA’s axial-flux electric motors with its AMG GT XX Concept car, but it seems that EV’s powerplant was just the tip of the iceberg. YASA has just claimed an unofficial world record for the highest-power density electric motor “in its class.”

Tim Woolmer, CTO at YASA, made the claim on LinkedIn, saying a new prototype motor it developed produces 550 kilowatts and weighs only 13.1 kilograms. That gives it an astounding power density of 42 kW/kg . The previous unofficial record? Helix, an electric drive system company, made a motor with a 23 kW/kg density.

To put that in freedom units, YASA’s prototype motor produces just over 737 horsepower and weighs only 28.9 pounds. That’s more power than a standard Hellcat engine, in a piece of equipment you can pick up and hold in your hands.

How did YASA do it? Details are thin, but Woolmer noted it didn’t use any exotic materials, believes the design is mass-producible at 10,000–50,000 units per year and touts “insane cooling performance.” Continuous power is “close” to the peak output using only standard cooling fluids, and Woolmer said the peak itself is good for about five seconds. YASA’s axial-flux motors are naturally more power dense than the radial flux motors used in EVs today thanks to the inherent design. (If you want to know the long, technical details, check out a deep dive on electric motor design here.)

Woolmer says YASA wasn’t trying to achieve a world record with its electric motor, saying it “accidentally” achieved the highest power density. The potential that such a motor has for production vehicles is great. A single electric motor with that much power taking up such little space at a relatively inconsequential weight would be a huge help for packaging, especially for sports cars.

Road & Track reached out to YASA to see what other details it would provide about this prototype electric motor, and we’ll update this post if we hear back. Theoretically, Mercedes-AMG products would be first up to take advantage of this motor tech, and the upcoming production version of the AMG GT XX is already set to use YASA’s axial-flux electric motor tech.